physics 2002 p3
TRANSCRIPT
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FORM TP 22139'
CARIBBEAN EXAMINATIONS COUNCIL
SECONDARY EDUCATION CERTIFICATE
EXAMINATION
PHYSICS
Paper 03 - General Proficiency
In addition to the 1 hour, candidates are alloweda
reading time of 10 minutes. Candidates must NOT
write in their answer booklets during this time.
2. ALL WORKING MUST BESHOWN in your answerbooklet, since marks willbe awarded for
correct steps incalculations.
Copyright 2001 Caribbean Examinations Council.
All rights reserved.
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State the law of conservation of energy and differentiate between kinetic and potential
energy. ( 3 marks)
(b) A spring-mass system oscillates between X and Y on a frictionless table as shown in
Figure 1.
Describe what energy transformations take place as the mass travels from X to Y. 0
is the equilibrium position of the spring. ( 5 marks)
(c) A 0.5 kg block slides from rest down an inclined plane as shown in Figure 2. The
velocity at the bottom of the plane is 6 m s-t. The vertical distance PO is 2.0 m
(g = 10 m s-Z)
(i) Calculate the potential energy at the top of the incline and the kinetic energy at
the bottom of the incline.
(iv) If part (iii) were performed on the moon where g = 2 m s-2, explain whether the
velocity at 0 would be greater or lesser than the velocity obtained in part (iii).
(12 marks)
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Describe an experiment to verify Snell's law of refraction. State what apparatus you
would use, give a brief description of the method you would use and state how you would
arrive at your conclusion. (8 marks)
(b) An optical device consists of two glass blocks of different indices of refraction, arranged
as shown in Figure 3. The refractive index from air to Medium 1 is 1.2. The refractive
index from Medium 1 to Medium 2 is 1.25.
Medium
1
Medium
2
(i) Iflight is incident at 60 on the block with the smaller refractive index, determine
the angles 81, 82, 83
, 84 and 85
.
(ii) What is the velocity of light in Medium 1?
c = 3 X 108 m S-1
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Figure 4 shows a simplified diagram of a permanent magnet d.c.motor (seen from one
end) in which a rectangular coil is suspended in a uniform magnetic field.
Current
into paper
Axis
of
rotation
Current
out of
paper
(i) Copy this diagram into your answer booklet. On your diagram, draw the
forces which turn the coil. These forces make up a couple that causes rotation
of the coil. Will the coil rotate in a clockwise or anticlockwise direction? Indicate
on your diagram the coil position which gives maximum value of the couple.
(ii) How would the speed of the motor be affected by an increase in the supply
voltage? Explain. (8 marks)
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(b) Electricity can be generated by passing a conducting liquid through a very strong
magnetic field. The electrical energy is extracted by suitably placed electrodes as shown
in Figure 5.
I
I
I
I
J----
"
Conducting
fluid
A, B -Magnetic poles pieces
C, D - Electrodes
A - North pole
B South pole
(i) By considering an element of fluid, XY, in the shape of a cylindrical rod,
determine the direction of current flow through the load RS. Give the name of
the rule you use.
(ii) In one version of this type of generator the conducting liquid is pumped through
the electrodes in a continuous circulating loop, thereby producing a d.c. output.
Explain why this arrangement produces only a d.c. output.
(iii) Suggest TWO possible modifications to the operation of this generator which
would result in an a.c. output. Select any ONE of your suggestions and explain
why it would work.
(iv) Suppose the liquid was not pumped and the load RS replaced by a battery. Would
the liquid move? Explain. What would be the overall effect of this change?(12 marks)
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What are the TWO principal ideas of the kinetic theory of matter? Describe the kinetic
theory model of the three states of matter. (8 marks)
Heat must either be added or removed to convert one state of matter to
another. Calculate the amount of heat energy which must be added to2.5 kg of
water at its boiling point in order to evaporate it completely.
(Specific Latent Heat of vaporization of water = 2 260 000 Jkg-i)
(ii) It is observed that the specific latent heat of vaporization is greater than the
specific latent heat of fusion for most substances. Use kinetic theory toexplain
this in terms of the separation of the particles in each state. (6 marks)
If the steam in part (b) (i) were captured in a closed container at 100 Cand then
heated, the pressure in the container would be observed to increase. Use kinetic
theory to explain this effect.
(ii) When a drop of a strongly coloured liquid (such as potassium d ichromate - abright yellow liquid) is added to a beaker of water, it is found that after some
time the entire contents of the beaker become a uniform colour. Use kinetic
theory to explain this phenomenon. (6marks)
Describe an experiment to determine the position of the centre of gravity of a
metal sheet of uniform thickness. Your account should include the apparatus
you would use and a brief account of a suitable procedure.
(ii) State the condition which the position of the centre of gravity of a body must
satisfy in order that the body be stable. (8 marks)
(b) Two uniform planks each of mass 10 kg and length 2 m are arranged as shown in
Figure 6.
D P
1----1
= - _ - ~ ~ - = = I ((i) Find the maximum value of x for which the top plank will remain in
equilibrium.
(ii) A 15 kg mass is placed at P. Draw a diagram showing the forces acting on the
upper plank when it is just about to topple. Use your diagram to calculate the
value of x for which the upper plank just begins Jo topple. (8 marks)
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(c) Two uniform rods both of length 2 m are arranged at right angles as shown in Figure 7,
D and E are the mid-points of rods AC and AD respectively.
A
< :
B
>
(i) In your answer booklet, draw a well labelled diagram of the arrangement,
showing the line of action of the weight of the arrangement relative to A, B,C,
D and E when it is
(ii) Hence, labelled diagrams of the arrangement as shown in Figure 7 and clearly
indicate the position of the centre of gravity ofthe arrangement relative to A, B,
C, D and E. (4 marks)