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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)