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` Student Number 2015 HIGHER SCHOOL CERTIFICATE MID-YEAR EXAMINATION Physics General Instructions Total marks - 75 Reading time – 5 minutes This paper has two parts, Part A and Part B Working time – 2 hours Part A – 20 marks Attempt Questions 1-20 Allow about 35 minutes for this part Write using black or blue pen Draw diagrams using pencil Part B – 55 marks Attempt Questions 21-30 Allow about 1 hour and 25 minutes for this part Use the multiple-choice answer sheet provided Write your Centre Number and Student Number at the top of this page, page 8, and on the multiple-choice answer sheet Disclaimer Every effort has been made to prepare this Examination in accordance with the Board of Studies documents. No guarantee or warranty is made or implied that the Examination paper mirrors in every respect the actual HSC Examination question paper in this course. This paper does not constitute ‘advice’ nor can it be construed as an authoritative interpretation of Board of Studies intentions. No liability for any reliance, use or purpose related to this paper is taken. Advice on HSC examination issues is only to be obtained from the NSW Board of Studies. The publisher does not accept any responsibility for accuracy of papers which have been modified. MIDPHY15_EXAM 1 2015 HIGHER SCHOOL CERTIFICATE MID-YEAR EXAMINATION PHYSICS Part A – 20 marks Attempt Questions 1-20 Allow about 35 minutes for this part Use the multiple-choice answer sheet provided for Questions 1-20 Select the alternative A, B, C or D that best answers the question. Fill in the response oval completely. Sample 2 + 4 = (A) 2 (B) 6 (C) 8 (D) 9 A B C D If you think you have made a mistake, put a cross through the incorrect answer and fill in the new answer. A B C D If you have changed your mind and have crossed out what you consider to be the correct answer, then indicate this by writing the word correct and drawing an arrow as follows: correct A 1 B C D An astronaut stood on bathroom scales on earth and recorded a reading of 110 kg. The same astronaut then went to planet X and recorded a reading of 80 kg. What is the acceleration due to gravity on planet X? (A) 1.38 ms-2 (B) 7.13 ms-2 (C) 13.5 ms-2 (D) 110 ms-2 MIDPHY15_EXAM 2 2 Students used a pendulum with mass m, string length L, and launch angle to calculate the acceleration due to gravity. Which of the following correctly represents the relationship measured for the period of a pendulum? (A) T L (B) T 1/L (C) T2 L (D) T m 3 Students compared the flight of a paper plane and a ball thrown across the room. Why will the equations for projectile motion not be accurate in predicting the path of the paper plane? (A) A paper plane has almost no mass. (B) A paper plane is not accelerated by gravity like the ball. (C) A paper plane is acting like an unpowered object. (D) A paper plane is acting like powered object. 4 A small pebble is dropped from a height and falls for 2.3 seconds. What was the height of drop? (A) 11.3 m (B) 16.1 m (C) 25.9 m (D) 51.8 m 5 Students carried out an experiment involving spinning around a cork at the end of a string in order to measure circular motion. How should students record the risk and precaution in this case? (A) Projectile hazard: be careful. (B) Projectile hazard: stand back 1 m from spinning cork. (C) Motion hazard: stop the cork from spinning fast. (D) Cork hazard: do not use a spinning cork. MIDPHY15_EXAM 3 6 What occurs to the value of R3/T2 for the planets in our solar system as we move out from Mercury top Neptune? (A) The value will increase. (B) The value will decrease. (C) The value will fluctuate. (D) The value will remain constant. 7 Which of the following is an equivalent statement of Einstein’s Principle of Relativity? (A) No experiment can be performed to determine the absolute motion of an object. (B) No experiment can be performed to determine the speed of light relative to a moving observer. (C) All motion is relative. (D) Light does not need a medium of propagation. 8 A student moves a magnet near a coil of wire with a few loops. There is a galvanometer attached across the ends of the coil. Which of the following correctly describes the action and the consequence on the voltage read by the galvanometer? (A) Increasing the motion of the magnet will decrease the voltage. (B) Increasing the number of loops in the coil will decrease the voltage. (C) Decreasing number of loops in the coil will decrease the voltage. (D) Decreasing the strength of the magnet will increase the voltage. 9 A rectangular coil made of one piece of wire on an axle turns in between rectangular pole pieces. The coil measures 10 cm along the turn axis and is 16 cm wide. What is the torque acting on this coil if a current of 2.6 A is flowing and the field strength is 0.045 T where the coil turns? (A) 9.36 x 10-4 Nm (B) 1.87 x 10-3 Nm (C) 0.0117 Nm (D) 18.72 Nm MIDPHY15_EXAM 4 10 What is the role of the commutator in a DC electric motor? (A) It switches the direction of the current in the coil every ½ turn of the rotor. (B) It switches the direction of the current in the external circuit every ½ turn of the rotor. (C) It switches the direction of the current in the coil every ¼ turn of the rotor. (D) It keeps the current in the coil travelling in the same direction as the rotor turns. 11 Students were moving a long loop of wire through the air and noted that a small fluctuating voltage occurred across the ends of the wire. Why did this happen? (A) Eddy currents caused the wire to heat up. (B) An emf was induced when the wire cut across the Earth’s magnetic field lines. (C) An magnetic field is in induced when charges move in the wire. (D) An emf was induced when the wire moved parallel to the Earth’s magnetic field lines. 12 The diagram represents two different regions of magnetic field. How does the flux in region X compare with the flux in region Y? (Note: The diagram is to scale.) region X region Y X X X X X X X X X X X X (A) The flux in X is into the page, and greater than the flux in Y. (B) The flux in X is out of the page, and greater than the flux in Y. (C) The flux in X is out of the page, and less than the flux in Y. (D) The flux in X is into the page, and equal to the flux in Y. MIDPHY15_EXAM 5 13 A transmission line is set up to take electricity to a new suburb. What happens to the resistance losses when the thickness of the transmission line is increased and all other factors remain the same? (A) The resistance losses will decrease. (B) The resistance losses will not be affected. (C) The resistance losses will increase. (D) The resistance losses are independent of wire thickness. 14 Which of the statements below is valid regarding how real voltage transformers work in a power grid? (A) The input electrical energy is equal to the output electrical energy. (B) The input electrical energy is converted into mechanical energy. (C) The input electrical energy is converted into heat energy and a lower amount of output electrical energy. (D) The input electrical energy is converted into heat energy, and the amount of output electrical energy can be higher or lower than the input electrical energy. 15 Thompson carried out early experiments with a cathode ray tube. Why did he make the cathode rays travel into a region of crossed electric and magnetic field inside the tube? (A) This forced the cathode rays to be deflected. (B) This alone allowed him to calculate the velocity of the cathode rays moving in a straight line. (C) This alone allowed him to calculate the charge of cathode rays. (D) This alone allowed him to calculate the charge to mass ratio of the cathode rays. 16 Students observed gas discharge tubes at different pressures and noticed that the tube with the lowest pressure did not show much of a light display, producing only a faint green glow. What is the correct explanation for this? (A) At low air pressure there is not enough gas atoms in the tube for fluorescence, and the cathode rays fluoresce upon hitting the glass. (B) At low air pressure there are too many gas atoms in the tube to fluoresce, while the green glow come from cathode rays hitting the glass. (C) The cathode rays become light rays and then fluoresce upon hitting the glass. (D) The cathode rays become UV rays and then fluoresce upon hitting the glass. MIDPHY15_EXAM 6 17 What did Hertz discover in his early experiments that involved the photoelectric effect? (A) Electromagnetic waves are transverse waves. (B) UV light shining on the cathode will increase the photocurrent. (C) UV light shining on the spark gap will increase the sparking. (D) Radio waves impinging on the spark gap will cause UV light to be emitted. 18 A semiconductor was made with a band gap of 2.53 eV. What wavelength of light will cause the electrons in the semiconductor to jump from the valence band to the conduction band? (A) 880 nm (B) 675 nm (C) 559 nm (D) 490 nm 19 Which of the following is not a property of a thermionic diode? (A) The device will operate with almost no warm up. (B) The device is brittle. (C) The device becomes very warm during operation. (D) The device can rectify a current. 20 What happens to the magnetic field of a magnet brought near a superconductor? (A) The magnetic field lines will not enter the superconductor and so they stop at the superconductor. (B) The magnetic field lines will not enter the superconductor and so they re-align around the superconductor. (C) The magnetic field lines will enter the superconductor and pass through. (D) The magnetic field lines will enter the superconductor and stop in the middle. MIDPHY15_EXAM 7 2015 HIGHER SCHOOL CERTIFICATE MID-YEAR EXAMINATION PHYSICS Centre Number Student Number Part B – 55 marks Attempt Questions 21-30 Allow about 1 hour and 25 minutes for this part Answer the questions in the spaces provided. The spaces provide guidance for the expected length of response. Extra writing space is provided on pages 18-20. If you use this space, clearly indicate which question you are answering. Show all relevant working in questions involving calculations. Question 21 (7 marks) A canon ball is fired at an initial speed of 42 ms-1 at an angle of 50° to the horizontal. The ball lands at the same horizontal level from which it is fired at. (a) Calculate the initial vertical and horizontal component of velocity for the cannon ball. 2 ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. (b) Calculate the maximum height of the cannon ball. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. ………………………………………………………………………………………. MIDPHY15_EXAM Question 21 continues over the page 8 2 Question 21 (continued) (c) Marks Calculate the velocity of the canon ball 3 seconds after launch. 2 1 ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… (d) State where along the path the velocity of the cannon ball is at its maximum. 1 ………………………………………………………………………………… ………………………………………………………………………………… Question 22 (5 marks) Galileo completed many experiments on motion. In one experiment, he is reported to have dropped two masses, which were the same size but of different weight, from the leaning tower of Pisa. (a) Explain the result of this experiment. 2 …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… (b) Explain how the result above would differ if the balls were the same size but one was made of foam (rough surface) and the other of metal (smooth surface). 3 ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. …………………………………………………………………………………………… MIDPHY15_EXAM 9 Question 23 (7 marks) Satellite A is put into orbit around planet Xena. Planet Xena has a moon called Tina, which is less than half the mass of Xena, and satellite B is put into orbit around Tina. The mass of Xena = 5.1 x 1024 kg . (a) Explain what the period of satellite A depends on according to Kepler’s 3rd law. 2 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (b) Calculate the orbital radius and the orbital speed of satellite A if it has a period of 6 hours. 2 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (c) Satellite B has the same orbital period as satellite A. Would the orbital radius of satellite B be larger, the same as, or smaller than the orbital radius of satellite A? Justify your response. 2 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ………………………………………………………………………………………………. (d) Outline how the orbital speed of satellite A would be affected if it split into two equal sized pieces orbiting at the initial altitude. ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 10 1 Question 24 (3 marks) A space ship is travelling at 98% the speed of light. An astronaut on board the rocket measures 10 seconds for the time taken for her cat to walk across the room. (a) Is there an experiment that the on board astronaut can do to be able to measure the rockets’ absolute velocity relative to a stationary ether? Justify your response. 2 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (b) Calculate the time taken for the cat to walk across the room according to a stationary outside observer. 1 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… Question 25 (5 marks) A Satellite is planned to be placed in a circular orbit 21 500 km above the Earth’s surface to be part of a GPS array. The satellite has a mass of 2000kg. Take the radius of the Earth to be 6 380 km and take the mass of the Earth form the data sheet. (a) Calculate the Gravitational Potential Energy of the satellite before it launched. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 11 1 Question 25 continued (b) Calculate the amount of work done against gravity to raise the satellite to its final orbit. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 12 2 Question 26 (6 marks) A length of copper wire is part of a simple circuit with a lamp and a battery and a switch. The copper wire is then placed in between the poles of a strong magnet and released. (a) Explain why the copper wire will not move when the switch is open, even though it is near the magnetic poles, but will move when the switch is closed. 4 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (b) The side view diagram below shows the wire between the magnet poles. There is a current of 3.9 A in the wire, and the wire is 12 cm long inside a uniform 55 mT magnetic field. State the magnitude and direction of the force from the magnetic field. N S I ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 13 2 Question 27 (7 marks) An early electricity pioneer set up a circuit with a voltage source and a solenoid coil and a switch. He then set up a circuit nearby that had a solenoid coil but no voltage source, with a magnetic compass placed near the solenoid. He noticed that the compass needle would move and flicker when the switch was constantly changed from on to off. (a) Identify the early electricity pioneer who carried this out, and state what the effect became known as. 2 ……………………………………………………………………………………………… ……………………………………………………………………………………………… (b) Account for the observation. 3 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… (c) Outline what the experimenter should do in order for the results here to become accepted by the scientific community. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 14 2 Question 28 (6 marks) Use a table to compare the AC coil motor with the AC induction motor in terms of structure, benefits and drawbacks. 6 ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… MIDPHY15_EXAM 15 Question 29 (5 marks) Marks B x C A y The length of the single loop ABCD is 0.9 m and its breadth is 0.5 m. Initially ABCD lies perpendicular to a uniform magnetic field that has a flux density of 0.5 T. D (a) Find the change in the magnetic flux penetrating loop ABCD, including units, when it rotates 90 around the axis xy, such that AB comes up out of the page. 2 (b) If the loop is rotating at 100 Hz, how long does it take to turn through 90? 1 (c) dΦ Faraday’s law is emf n . . Determine the emf generated in ABCD as it dt is turned through 90. 1 MIDPHY15_EXAM 16 Question 30 (4 marks) MIDPHY15_EXAM Marks 17 Part B extra writing space. If you use this space, clearly indicate which question you are answering. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ MIDPHY15_EXAM 18 Part B extra writing space. If you use this space, clearly indicate which question you are answering. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ MIDPHY15_EXAM 19 Part B extra writing space. If you use this space, clearly indicate which question you are answering. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ MIDPHY15_EXAM 20 Student Number PHYSICS – MULTIPLE-CHOICE ANSWER SHEET ATTEMPT ALL QUESTIONS Question MIDPHY15_EXAM 1 A B C D 2 A B C D 3 A B C D 4 A B C D 5 A B C D 6 A B C D 7 A B C D 8 A B C D 9 A B C D 10 A B C D 11 A B C D 12 A B C D 13 A B C D 14 A B C D 15 A B C D 16 A B C D 17 A B C D 18 A B C D 19 A B C D 20 A B C D 21 Blank Page MIDPHY15_EXAM 22