Download AL Physics 1999 Paper 2

AL Physics
1999 Paper 2
Section B
Answer any THREE questions from this section. Write your answers in the ANWER
BOOK provided. You should spend 1 hour and 15 minutes on this section
1.(a)A small ball is projected horizontally with a certain speed from a height of 1 m above a
smooth expanse of ground .The ball falls under gravity, hits the ground and bounces up .
(i)Assuming that no energy is lost in the process, sketch graphs to show how the vertical
component of the velocity and the acceleration of the ball vary with time to the point when
the ball bounces up to the original level. Label the axes wherever possible. Describe the
force(s) acting on the ball and briefly explain the shape of the graphs.
(ii)State the change(s),if any ,to the graphs in (a)(i)for the following cases. Briefly explain
your answer.
(I)A ball of greater mass is used
(II)The projection speed is increased
(III)Some kinetic energy is lost when the ball hits the ground
(iii)Discuss whether the momentum of the ball is conserved when it hits the ground
(12 marks)
(b)With the apparatus available in a school laboratory, describe a simple experiment to
investigate the dependence of the stopping distance of a vehicle on its initial kinetic energy
under the action of a constant resistive force. State and describe how to verify the expected
result .State the source(s) of error.
(4 marks)
2.(a)(i)With the aid of a diagram, explain how stationary stationary waves are formed.
(ii)Explain the following by referring to various phenomena of waves.
(I)Radio waves of long wavelengths can propagate long distances
(II)The voice of one of your teachers can be heard and identified before he enters the
classroom
(III)Two violin players are playing the same note together for a few seconds and a listener
finds that the intensity of the sound seems to vary with time
(IV)A radio receiver seems to work better in some parts of a room than in other parts
(V)Polaroid sunglasses can effectively reduce the glare of the sun reflected from the sea
(10 marks)
(b)You are asked to measure the wavelength of red light using a diffraction grating. With
the aid of a diagram, describe how you would carry out the experiment and state any
precautions. List the measurements that you would take and the major source of error.
(6 marks)
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3.(a)A parallel-plate capacitor of capacitance C and a resistor of large resistance R are
connected in series with a battery of e.m.f. ε having negligible internal resistance.
(i)Sketch graphs to show the time variation of the voltage across the capacitor and the
current in the circuit after closing switch S. Briefly explain your answer
(ii)A student uses a voltmeter of resistance R to check the voltage across the capacitor and
finds that the reading falls from an initial value .ε/2.Briefly explain why this is so.
(iii)With switch S closed, the plates of the capacitor are pulled apart slightly. Describe and
explain the possible change(s) in the charge and energy stored in the capacitor when the
steady state is reached
(8 marks)
(b)(i)You are asked to demonstrate the change in the terminal p.d. of a supply when
delivering a current .With the aid of a diagram, describe how you would carry out the
experiment using a 12 V 24 W ray box lamp and some additional apparatus .Explain how
the internal resistance of the supply could be estimated and state the source(s) of error.
(ii)(I)State and discuss significance of the order of magnitude of the internal resistance of a
5 Kv E.H.T
(II)A 12 V car battery is designed to deliver a current of a hundred amperes to operate the
starting motor. Explain why the headlights would dim when a car is started with the
headlights on
(8marks)
4.(a)(i)With reference to the intermolecular forces ,kinetic energy and potential energy of
water molecules ,describe the changes involved in changing an ice cube at 0°C to steam at
100°C. Do you agree that skin burnt by steam at 100°Cis more severe than water at
100°C?Explain briefly.
(ii)Distinguish the terms heat, work and internal energy .Illustrate your answer by
describing the energy conversions in a steam turbine.
(9 marks)
(b)(i)To check for oil leaks in underground pipelines ,a radioactive source is put into the
pipeline and the radiation is detected on the ground .Discuss what kind of radioactive
sources is/are suitable for this purpose
(ii)
Radioactive substance
Half-life
Radiation emitted
Radon-222
Iodine-131
α
γ
3.8days
8days
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(I)Radon gas is usually present in the environment of concrete buildings. Explain why
radon is considered to be hazardous to human beings and why opening windows is a way to
minimize its hazardous effects.
(II)Iodine-131 is used for investigating the absorption of iodine by the thyroid
gland .Discuss the suitability of using ioding-131 for this purpose,
(7 marks)
5.(a)(i)Using a solenoid connected to an a.c. source of variable frequency, describe a simple
experiment to investigate how the induced e.m.f. in a coil depends on the rate of change of
the magnetic flux linkage through it .List the apparatus used and describe the observation.
(ii)State THREE factors that would affect the magnetic flux linkage through a coil
(9 marks)
(b)Referring to appropriate physical laws ,explain the following.
(i)Sparks occur when opening the switch of a circuit with an electromagnet in it.
(ii) there is potential difference developed between the wing-tips of an aircraft when it is
flying horizontally in air
(iii)The pointer of a moving-coil meter stops at the final steady value as soon as it reaches
that value and shows no further oscillation.
(7 marks)
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