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TASMANIAN QUALIFICATIONS AUTHORITY PLACE LABEL HERE Tasmanian Certificate of Education PHYSICS Senior Secondary 5C Subject Code: PHY5C External Assessment 2005 Part 1 Time: approximately 45 minutes On the basis of your performance in this examination, the examiners will provide a result on the following criteria taken from the syllabus statement: Criterion 6 Demonstrate knowledge and understanding of the impact of science on society and the environment. Criterion 7 Demonstrate knowledge and understanding of Newtonian mechanics including gravitational fields. Pages: Questions: © 15 6 Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian Qualifications Authority. Physics – Part 1 CANDIDATE INSTRUCTIONS Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this examination paper. Answer ALL questions. Answers must be written in the spaces provided on the examination paper. NOTE: Candidates have a choice. Answer either Question 5 OR Question 6, but not both. In total it is recommended that you spend approximately 45 minutes answering questions in this part. The 2005 Physics Formula Sheet can be used throughout the examination. No other printed material is allowed into the examination. A set of spare diagrams has been provided in the back of the answer booklet for you to use if required. If you use a spare diagram, you MUST indicate you have done so in your answer to that question. Page 2 Physics – Part 1 For Marker Use Only Question 1 This question assesses Criterion 7. The force-distance graphs below are for a conventional bow and a more complex ‘compound’ bow. They show how the force exerted on and by the bow-string varies with the distance (the ‘draw’) the bowstring has been pulled from its rest position. Rest position of bowstring Compound bow 0 draw sw Force (N) 100 200 300 Conventional bow 0 (a) 0.1 0.2 0.3 0.4 0.5 0.6 Draw (displacement from rest position ) (m) Which of the two bows will give the greater maximum acceleration to the same arrow? Justify your answer. (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) The work done in extending the bowstring 0.6 m is the same for each of the two bows shown. What is the value of this work? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) The archer must hold the bow at full draw for sometime while aiming the arrow. What advantage does the compound bow give to the archer? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Page 3 /7 Physics – Part 1 For Marker Use Only Question 2 This question assesses Criterion 7. Last year SpaceShipOne became the first privately owned manned vehicle to reach space. (a) At a particular instant during the vertically upward climb ‘flight’ of SpaceShipOne, its rocket was ejecting 30 kg of fuel per second with an exhaust velocity of 2.5 ×10 3 ms−1. Show that the value of the thrust produced by this rocket was 7.5 ×10 4 N. (3 marks) € € ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) If the mass of S p a c e S h i p O n e at the instant referred to in part (a) were 2 500 kg, show that its upward acceleration was 20 ms−2 . (3 marks) ............................................................................................................................................. ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Complete the following diagrams to show the main forces acting on SpaceShipOne. (i) When it is accelerating upwards under the influence of the rocket. (2 marks) (ii) When it is returning to Earth, and slowing down under the influence of air drag. (2 marks) Question 2 continues opposite. Page 4 Physics – Part 1 Question 2 (continued) (d) The rocket engine was turned on when SpaceShipOne was at a height of 15 000 m. Its initial vertical velocity at this height was 0 and it accelerated vertically upwards at a constant 21 ms−1 for 80 seconds. For Marker Use Only What was its height above the Earth’s surface when the rockets stopped firing? (3 marks) ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /13 Page 5 Physics – Part 1 For Marker Use Only Question 3 This question assesses Criterion 7. The Earth revolves around the sun in an approximately circular orbit of radius 1.496 × 108 km. (a) Knowing that the Earth takes exactly one year (3.16 × 107 seconds) to revolve around the sun, show that the mass of the sun is 1.98 × 1030 kg. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Astronomers are able to measure the masses of distant stars by observing the orbits of planets (or other objects) around the star. What information would an astronomer need to measure the mass of a star in this way? In particular, will the astronomer need to know the mass of the orbiting planet? Explain. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) What is the speed of the Earth in its orbit around the sun? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /9 Page 6 Physics – Part 1 For Marker Use Only Question 4 This question assesses Criterion 7. Compact disc (CD) drives have now reached rotational speeds that are very high. In a 52× CD drive, the discs are rotating with a frequency of 10 400 rpm which is 52 times faster than the ‘base’ frequency of 200 rpm. (1 rpm = 1 revolution per minute.) (a) Show that the period of rotation of a disc in a 52× CD drive is 5.77 ms. (1 mark) ............................................................................................................................................. ............................................................................................................................................. (b) The discs have a radius of 5.8 cm. Show that the centripetal acceleration of a point on the edge of the disc is equal to 6.9 ×10 4 ms−2 . (3 marks) ............................................................................................................................................. ............................................................................................................................................. € € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Experimental tests have shown that the maximum acceleration that can be sustained by the edge of a good-quality spinning disc before it disintegrates is 4.0 ×10 5 ms−2 . Discuss what is likely to be the maximum safe speed of future CD drives. (3 marks) There is no ‘correct’ answer to this question. You will be marked on how well you use the data provided to give a reasoned answer. € € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /7 Page 7 Physics – Part 1 Answer EITHER Question 5 OR Question 6 For Marker Use Only Question 5 This question assesses Criterion 6. During the year, a newspaper article claimed that many drivers do not understand the basic physics of safe driving. In each of the following questions you are given a quote from the article. Using your knowledge of physics, outline how you would convince a friend that the information provided in the quote is at least approximately correct. (a) ‘The stopping distance of a car with a number of passengers is a lot more than the stopping distance with only the driver present in the car.’ (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) ‘If the speed of a car is doubled, the stopping distance becomes four times greater.’ (Hint: kinetic energy could provide the basis of one solution.) (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 5 continues opposite. Page 8 Physics – Part 1 Question 5 (continued) (c) ‘The stopping distance of a car on a wet road is a lot more than on that road when dry.’ For Marker Use Only NB. A clear discussion of forces involved, including force diagrams, would assist your answer to this question. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /12 Page 9 Physics – Part 1 Answer EITHER Question 5 OR Question 6 For Marker Use Only Question 6 This question assesses Criterion 6. In 2004 SpaceShipOne became the first privately owned ‘spaceship’ to reach an altitude of over 100 km, paving the way for future space tourism. During the trip, the pilot of SpaceShipOne experienced dramatic changes in apparent weight. (a) • Initially, as SpaceShipOne accelerated upward, the apparent weight was equal to about three times normal weight. • When the rocket engines were turned off, there was a period of weightlessness. • Finally, as SpaceShipOne re-entered the atmosphere, apparent weight reached values up to six times normal weight before the space ship glided gently back to Earth. Why does the pilot feel ‘weightless’ during part of the flight? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 6 continues opposite. Page 10 Physics – Part 1 Question 6 (continued) (b) Why does the pilot feel much heavier than normal during two different parts of the flight? Include force diagrams in your answer. For Marker Use Only (5 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Is SpaceShipOne, in its present form, suitable for ordinary tourists? If not, what aspects of the flight would have to change to make it suitable for tourists? (5 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Page 11 /12 Physics – Part 1 SPARE DIAGRAMS Question 2 (c) Page 12 Physics – Part 1 BLANK PAGE Page 13 Physics – Part 1 BLANK PAGE Page 14 Physics – Part 1 BLANK PAGE Page 15 TASMANIAN QUALIFICATIONS AUTHORITY PLACE LABEL HERE Tasmanian Certificate of Education PHYSICS Senior Secondary 5C Subject Code: PHY5C External Assessment 2005 Part 2 Time: approximately 45 minutes On the basis of your performance in this examination, the examiners will provide a result on the following criteria taken from the syllabus statement: Criterion 6 Demonstrate knowledge and understanding of the impact of science on society and the environment. Criterion 8 Demonstrate knowledge and understanding of electricity and magnetism. Pages: Questions: © 11 5 Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian Qualifications Authority. Physics – Part 2 CANDIDATE INSTRUCTIONS Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this examination paper. Answer ALL questions. Answers must be written in the spaces provided on the examination paper. In total it is recommended that you spend approximately 45 minutes answering the questions in this part. The 2005 Physics Formula Sheet can be used throughout the examination. No other printed material is allowed into the examination. A set of spare diagrams has been provided in the back of the answer booklet for you to use if required. If you use a spare diagram, you MUST indicate you have done so in your answer to that question. Page 2 Physics – Part 2 For Marker Use Only Question 7 This question assesses Criterion 8. In an accelerator protons are accelerated through a potential difference of 1.0 ×10 6 volts. (a) What is the speed of the protons when they leave the accelerator? (2 marks) ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) € When the protons enter a zinc target, the closest distance they come to a zinc nucleus is 8 ×10−14 m. Show that the force of repulsion between the proton and nucleus at this distance is about 1 N. The charge on the zinc nucleus has value 30 times the charge on the electron. (3 marks) p Zn -14 8 × 10 m ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /5 Page 3 Physics – Part 2 For Marker Use Only Question 8 This question assesses Criterion 8. The electron beam in a cathode ray tube (CRT) passes through crossed electric and magnetic fields which have been adjusted so that the electric and magnetic forces on the electrons cancel. Coil with electric current Electric field down Electron gun Magnetic field into page Electron beam (a) (b) On the diagram show: (i) The sign of the electric charge (+ or -) on each of the parallel plates. (1 mark) (ii) The direction of the electric current within the coil. (1 mark) What is: (i) The direction of the electric force on the electron beam. (1 mark) .................................................................................................................................... (ii) The direction of the magnetic force on the electron beam. (1 mark) .................................................................................................................................... (c) Given the following information, show that the speed of the electrons in the above diagram is 2.0 ×10 7 ms−1. (2 marks) € Potential difference between plates of capacitor = 5.00 ×10 2 volt Distance between plates = 5.00 cm € Magnetic field strength = 5.00 ×10−4 T € ............................................................................................................................................. ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 8 continues opposite. Page 4 Physics – Part 2 For Marker Use Only Question 8 (continued) The magnetic field is now switched off. (c) Show that the value of the acceleration of the electrons between the plates due to the remaining electric field is 1.76 ×1015 ms−2 . (2 marks) ............................................................................................................................................. € € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (d) If the effective length of the plates is 10.0 cm what is the direction of the electron beam as it leaves the space between the plates? (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Page 5 /12 Physics – Part 2 For Marker Use Only Question 9 This question assesses Criterion 8. In the following problems, changes to the current in a primary coil induce a current in a secondary coil placed beside it. In each case sketch on the diagram: • the magnetic field along the axis of the primary coil • the induced magnetic field along the axis of the secondary coil • the induced current in the secondary coil. (3 marks) (3 marks) (3 marks) NB: Each coil is perpendicular to the page. The solid lines represent wire in front of the coil and the dotted lines represent wire to the rear of the coil (a) The current in the primary coil is increasing. Primary coil (b) (c) Secondary coil Movement The primary coil is moving towards the secondary coil. Primary coil Secondary coil Primary coil Secondary coil A piece of iron is being pushed into the primary coil. Iron Page 6 /9 Physics – Part 2 For Marker Use Only Question 10 This question assesses Criterion 8. (a) A straight wire carries an electric current of 5.0 A vertically upwards. What is the magnetic field strength (magnitude and direction) at a point 5.0 cm east of the wire? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) (i) A wire, at a distance d inside the wall of a house, carries a current I vertically upwards. At a point P, at a distance r from the wall as shown in the diagram, the magnetic field produced by the wire is equal to B. If I, d, r and B are measured in SI units, show that the following equation holds. (2 marks) kI r = −d B € Wire d r P Surface of wall ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 10 continues over the page. Page 7 Physics – Part 2 Question 10 (continued) (ii) For the situation described in part (i) (on the previous page), the graph below shows the results of measuring the value of the magnetic field B at different distances r from the wall. For Marker Use Only Distance r from wall vs 1/Magnetic Field Strength 0.1 0.08 Distance From Wall r (m) 0.06 0.04 0.02 0 -0.02 0 20000 40000 60000 80000 100000 -0.04 -0.06 -0.08 1/Magnetic Field Strength (1/T) Use the graph to determine: • • the value of the current I flowing in the wire the distance of the wire from the surface of the wall. Show your working. (5 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Page 8 /10 Physics – Part 2 For Marker Use Only Question 11 This question assessed Criterion 6. Airport security uses PI (pulse induction) systems to detect metallic objects on passengers. Powerful bursts of electric current lasting a very short time (a few microseconds) are fed into a large coil through which the passenger walks. The coil generates a pulse of magnetic field that passes through and around a passenger. Electric currents induced in a metallic object present on or in the passenger generate a magnetic field which can be detected. (a) Explain why the electric current and its associated magnetic field are made to switch on and off in a very short time. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) What types of materials can be detected (for example, do the materials have to be magnetic)? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) What dangerous materials do PI systems not detect? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 11 continues over the page. Page 9 Physics – Part 2 Question 11 (continued) (d) Describe some situations in which PI systems might give a false alarm. (2 marks) For Marker Use Only ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (e) What are other possible weaknesses in a PI system? (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /12 Page 10 Physics – Part 2 SPARE DIAGRAMS Question 9 (a) Primary coil Secondary coil Movement (b) Primary coil Secondary coil Primary coil Secondary coil (c) Iron Page 11 TASMANIAN QUALIFICATIONS AUTHORITY PLACE LABEL HERE Tasmanian Certificate of Education PHYSICS Senior Secondary 5C Subject Code: PHY5C External Assessment 2005 Part 3 Time: approximately 45 minutes On the basis of your performance in this examination, the examiners will provide a result on the following criteria taken from the syllabus statement: Criterion 6 Demonstrate knowledge and understanding of the impact of science on society and the environment. Criterion 9 Demonstrate knowledge and understanding of the general principles of wave motion. Pages: Questions: © 15 5 Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian Qualifications Authority. Physics – Part 3 BLANK PAGE Page 2 Physics – Part 3 CANDIDATE INSTRUCTIONS Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this examination paper. Answer ALL questions. Answers must be written in the spaces provided on the examination paper. In total it is recommended that you spend approximately 45 minutes answering the questions in this part. The 2005 Physics Formula Sheet can be used throughout the examination. No other printed material is allowed into the examination. A set of spare diagrams has been provided in the back of the answer booklet for you to use if required. If you use a spare diagram, you MUST indicate you have done so in your answer to that question. Page 3 Physics – Part 3 For Marker Use Only Question 12 This question assesses Criterion 9. The graph below shows how displacement varies with time for a particle oscillating in a sound wave. The speed of the sound wave is 340 ms−1. Displacement (mm) of particle in sound wave vs time (ms) € 0.2 Displacement (millimetres) 0.15 0.1 0.05 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -0.05 -0.1 -0.15 -0.2 Time (milli seconds) (a) Determine the: (4 marks) (i) period: ....................................................................................................................... (ii) frequency: .................................................................................................................. .................................................................................................................................... (iii) wavelength: ............................................................................................................... .................................................................................................................................... Question 12 continues opposite. Page 4 Physics – Part 3 Question 12 (continued) (b) By drawing an appropriate tangent to the graph, determine the speed of the oscillating particle at time 1.0 ms. Explain your working below. (6 marks) For Marker Use Only ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /10 Page 5 Physics – Part 3 For Marker Use Only Question 13 This question assesses Criterion 9. Diamond has a refractive index of 2.42. (a) Show that the critical angle for light passing from diamond to air is 24.4 degrees. (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) The following diagrams show light entering diamonds that have been cut in two different shapes. In each case, sketch the subsequent path of the light ray shown. (4 marks) 20° 140˚ 45° 90˚ Question 13 continues opposite. Page 6 Physics – Part 3 Question 13 (continued) (c) The best diamonds are cut in such a way that light entering them is reflected back outward. In view of your answer to part (b), what advice would you give to a diamond cutter? (4 marks) For Marker Use Only ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /11 Page 7 Physics – Part 3 For Marker Use Only Question 14 This question assesses Criterion 9. In the following questions you should illustrate your answers by drawing the appropriate wavefronts on the given diagrams. (a) A series of water waves passes through two gaps in a solid breakwater. Sketch and describe the wave pattern between the breakwater and the shoreline. (3 marks) Shoreline Incoming wavefronts ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 14 continues opposite. Page 8 Physics – Part 3 Question 14 (continued) (b) Water waves strike an island in deep water. Sketch and describe the wave pattern on the far side of the island. (3 marks) For Marker Use Only Island Incoming wavefront ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /6 Page 9 Physics – Part 3 For Marker Use Only Question 15 This question assesses Criterion 9. (a) A violin string has mass 1.0 g, a length 0.35m and a tension of 121 N. Show that the speed of the transverse wave that travels along the string is 206 ms−1. (3 marks) ............................................................................................................................................. ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) What is the fundamental frequency of vibration of the violin string in part (a)? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) Sometimes the violinist will lightly touch the string halfway along its length to produce a musical sound which has a higher frequency than the fundamental. Explain what is happening, and illustrate your answer by drawing a standing wave pattern for the resulting wave. (3 marks) Finger lightly touches here ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /9 Page 10 Physics – Part 3 For Marker Use Only Question 16 This question assesses Criterion 6. A knowledge of the physics of tsunami waves (such as the tragic tsunami that struck Asia in December 2004) could help to prevent loss of life in the event of future tsunamis. The following wave diagram, which is not to scale, shows a typical idealised wave profile for a tsunami both in the deep ocean and as it approaches the shore. Deep ocean Speed Wavelength Amplitude Approaching shore v = 50 kph λ = 50 km A = 20 m v = 700 kph λ = 700 km A = 0.5 m Ocean floor (a) Explain the following observations in terms of the data given above. (i) Ships in the open ocean usually do not detect the passage of a tsunami beneath them, even though the waves cause vast destruction at the shoreline. (1 mark) .................................................................................................................................... .................................................................................................................................... (ii) The first sign that a tsunami is about to strike a coastline may be a lowering of the sea level there, exposing large areas of the shore. (2 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... Question 16 continues over the page. Page 11 Physics – Part 3 Question 16 (continued) (iii) At the shoreline, tsunami waves have amplitudes that may be comparable to the amplitudes of ordinary surf waves, yet the tsunami waves cause far more damage than surf waves. Note that the wavelengths of surf waves are typically a few tens of metres. (2 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (iv) The first destructive wave is often followed by other even more destructive waves. (1 mark) .................................................................................................................................... .................................................................................................................................... (v) Tsunami waves travelling across the ocean will bend around large land obstacles. (See the accompanying map of wave front bend line) (2 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... India Sumatra (Indonesia) Epicentre Times of travel from epicentre (in hours) Question 16 continues opposite. Page 12 For Marker Use Only Physics – Part 3 Question 16 (continued) (b) To reduce loss of life in the event of future South-East Asian tsunamis, early-warning systems will have to be installed so that the presence of an ocean tsunami can be detected and warning sirens on the shore sounded. For Marker Use Only Public education will also be required as this quotation shows: ‘People along the Japanese coasts, along the coasts of California… are taught to move away from the coasts. But a lot of these people in the area where this occurred … probably had no kind of lessons or any knowledge of tsunamis because they are so rare.’ What are some likely problems in setting up such preventative measures in Asia, and in making them work when the next tsunami arrives? Note: as part of your answer to this question consider the travel time of a tsunami across a few hundred or a few thousand kilometres of ocean, shown in the map opposite.) (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /12 Page 13 Physics – Part 3 SPARE DIAGRAMS Question 13 (b) 20° 140˚ 45° 90˚ Question 14 (a) Shoreline Incoming wavefronts Page 14 Physics – Part 3 SPARE DIAGRAMS Question 14 (b) Island Incoming wavefront Question 15 (c) Finger lightly touched here Page 15 TASMANIAN QUALIFICATIONS AUTHORITY PLACE LABEL HERE Tasmanian Certificate of Education PHYSICS Senior Secondary 5C Subject Code: PHY5C External Assessment 2005 Part 4 Time: approximately 45 minutes On the basis of your performance in this examination, the examiners will provide a result on the following criteria taken from the syllabus statement: Criterion 6 Demonstrate knowledge and understanding of the impact of science on society and the environment. Criterion 10 Demonstrate knowledge and understanding of the practical nature of light and atomic and nuclear physics. Pages: Questions: © 15 5 Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian Qualifications Authority. Part 4 CANDIDATE INSTRUCTIONS Candidates MUST ensure that they have addressed ALL of the externally assessed criteria on this examination paper. Answer ALL questions. Answers must be written in the spaces provided on the examination paper. In total it is recommended that you spend approximately 45 minutes answering the questions in this part. The 2005 Physics Formula Sheet can be used throughout the examination. No other printed material is allowed into the examination. A set of spare diagrams has been provided in the back of the answer booklet for you to use if required. If you use a spare diagram, you MUST indicate you have done so in your answer to that question. Page 2 Part 4 Question 17 This question assesses Criterion 10. The diagram shows energy levels for a hydrogen atom. (The ground state has been omitted from the diagram.) (a) n=∞ PE = 0 n=5 n=4 PE = -0.87 × 10-19J PE = -1.36 × 10-19J n=3 PE = -2.40 × 10-19J n=2 PE = -5.43 × 10-19J Show that the wavelength of the photon emitted when an electron changes from the n = 3 to the n = 2 level is equal to 656 nm. (2 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) The visible wavelengths for hydrogen form a spectrum which has the appearance shown when viewed in a spectroscope. Series Limit Hδ Hγ 364.5 410 434 Hβ Hα 486 Wavelength (nm) 656 On the energy level diagram above, draw and label the electron transitions which produce light of wavelength: (i) 486 nm (the Hβ line in the spectrum). (1 mark) (ii) 364.5 nm (the series limit in the spectrum). (1 mark) Question 17 continues over the page. Page 3 For Marker Use Only Part 4 Question 17 (continued) (c) The following spectrums show the wavelengths emitted by mercury and xenon lamps as observed in a spectroscope. For Marker Use Only Xenon Mercury 400nm UV (i) Blue 500nm Green 600 nm Yellow 700nm Red What do the two spectrums tell us about how the electron energy transitions in xenon compare with those in mercury? No calculations are required. (3 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... (ii) To the human eye, light produced by a xenon lamp appears to be nearly white, whereas light produced by a mercury lamp appears ‘unnatural’ and somewhat harsh. How could you explain this in terms of the spectrums shown? (2 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... /9 Page 4 Part 4 For Marker Use Only Question 18 This question assesses Criterion 10. Caesium has a work function of 3.04 ×10−19 J. (a) What is the longest wavelength of light that will just cause the emission of photoelectrons from caesium? (2 marks) € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) What is the maximum energy of photoelectrons emitted when caesium is illuminated with light of wavelength 500nm? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /5 Page 5 Part 4 Question 19 This question assesses Criterion 10. Molybdenum-99, produced in nuclear reactors, is supplied to hospitals as a source of technetium-99. The molybdenum-99 has a half-life of 66 hours. (a) If a molybdenum source is supplied to a hospital with an initial activity of 7.4 ×1013 Bq, what will its activity be after two weeks (336 hours)? (3 marks) ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Show that the number of atoms of molybdenum-90 originally supplied to the hospital was 2.54 ×1019 . (3 marks) ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) What was the mass of molybdenum-90 supplied to the hospital? (3 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 19 continues opposite. Page 6 For Marker Use Only Part 4 Question 19 (continued) (d) Radioactive isotopes are produced either by neutron bombardment in a nuclear reactor or by bombardment with ions that have been accelerated through a high potential difference in an accelerator. (i) For Marker Use Only An equation for the production of iodine-131 in a reactor is: 235 U 92 + 1 n 0 → 131 I 53 + 99 Y 39 1 0 + 5 n Explain why this reaction could not be performed using an accelerator. (1 mark) .................................................................................................................................... € .................................................................................................................................... (ii) A typical accelerator induced reaction is: 68 Zn 30 + 1 p 1 → 67 Ga 31 1 0 + 2 n Relative isotopic masses are: € € € € 68 Zn 30 1 p 1 67 Ga 31 1 n 0 € 67.92713 1.007825 66.92804 1.008665 Explain why the protons must be given high energies to enable this reaction to proceed. (3 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... /13 Page 7 Part 4 Question 20 This question assesses Criterion 10. In a hospital, cancer cells may be killed using a beam of high energy X-rays or gamma rays. X-rays are produced by accelerating an electron beam through a high potential difference into a tungsten target. (a) If the electrons have been accelerated through a potential difference of 2.0 ×10 6 V, show that the minimum wavelength of the X-rays emitted is 6.21×10−13 m. (2 marks) ............................................................................................................................................. € ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. (b) What is the momentum of photons of X-rays which have the wavelength of 6.25 ×10−14 m? (2 marks) ............................................................................................................................................. ............................................................................................................................................. € ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (c) When destroying cancer cells using the high-energy beam of X-rays, it is important to maintain a narrow beam which does not spread out into the healthy tissue surrounding the cancer. Unfortunately, some of the X-ray photons undergo ‘Compton scattering’. (i) Explain what is meant by ‘Compton scattering’. (2 marks) .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... Question 20 continues opposite. Page 8 For Marker Use Only Part 4 Question 20 (continued) (ii) What will be the effect of ‘Compton scattering’ on the beam of X-rays passing through the tissue? Explain. (3 marks) For Marker Use Only .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... .................................................................................................................................... /9 Page 9 Part 4 For Marker Use Only Question 21 This question assesses Criterion 6. Australian hospitals acquire most of their radioisotopes from a nuclear reactor at Lucas Heights near Sydney. A new reactor (OPAL) is being constructed to replace the aging HIFAR reactor. Some of the isotopes that are manufactured, together with their half-lives, are: (a) Molybdenum-99 66 hours Iodine 131 Cobalt 60 8 days 5.3 years Regular supplies needed by many hospitals Sources generally need to have very high activity Some people have suggested that we should not construct a new reactor but should instead import radioactive isotopes from overseas. Discuss at least two problems that might be associated with importing such isotopes. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. (b) Discuss at least two potential areas of concern in establishing a nuclear reactor in Australia, and in particular in suburban Sydney. (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. Question 21 continues opposite. Page 10 Part 4 Question 21 (continued) (c) Cobalt-60 is used in hospitals as a source of high-energy photons for treating cancer. In recent years, developed countries have been replacing cobalt-60 sources with highenergy X-ray machines. For Marker Use Only What would be some advantages of using X-ray machines rather than using a radioactive source? (For the purposes of this discussion, you can assume that the photons provided by the cobalt-60 source and by the X-ray machine have the same effect on cancer cells.) (4 marks) ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. /12 Page 11 Part 4 SPARE DIAGRAM Question 17 (b) Series Limit Hδ Hγ 364.5 410 434 Hβ Hα 486 Wavelength (nm) 656 Page 12 Part 4 BLANK PAGE Page 13 Part 4 BLANK PAGE Page 14 Part 4 BLANK PAGE Page 15
