UNEB UCE

535/1

## 2¼ hours

UGANDA NATIONAL EXAMINATION BOARD

Uganda Certificate of Education

PHYSICS

Paper 1

Time: 2¼ hours

1991 PAPER 1

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SECTION A

1.  The process where by the nuclei of light element combine to form heavier nuclei is called

A.  fission B.  fusion C.  ionization D.  radioactivity

2.  When a plastic rod is rubbed with a dry piece of cloth, the rod and piece of cloth will

A.  both acquire negative charges B.  both acquire positive charges

C.  acquire positive charges  D.  have no charge

3.

The diagram above shows air trapped by a column of mercury in a J-tube. The atmospheric pressure is 76cmHg. At what pressure is the enclosed air

A.  10cmHg B.  66cmHg C.  76cmHg   D.  142cmHg

4.  On a cool day, a metal feels cold to the touch because

A.   metals contain less heat

B.  the temperature of the metal is the same as that of the surroundings

C.  the temperature of the metal is less than that of the surroundings

D.  the metal conducts the heat away form the hand

5.  A hippopotamus can easily walk on mud without sinking while a goat will sink because

A.   a hippopotamus has more weight than a goat

B.   the centre of gravity of a hippopotamus is lower than that of a goat

C.   a hippopotamus exerts more pressure on the ground than a goat

D.   a hippopotamus exerts less pressure on the ground than a goat

6.

The diagram above shows two perpendicular forces acting on an object of mass 5kg. Calculate the magnitude of the acceleration of the object

A.  0.6ms-1 B.  0.8ms-1 C.1.0ms-1 D. 1.4ms-1

7.   An electric toaster plate rating is 220-240V, 750W. The fuse is

A.  1A B.  3A C.  5A D.  13A

8.   If X is an isotope of Y, then the

A.  atomic mass of X is equal to that of Y

B.  atomic mass is equal to the atomic number of Y

C.  atomic number of X is equal to that of Y

D.  atomic number of X is equal to the atomic mass of Y

9.  Which of the following make a pair of complementary colours?

A.  blue and yellow B.  green and red

C.  green and yellow D.  yellow and magneta

10.  Oil spread over stagnant water kills mosquito larvae by

A.   covering the water surface and cutting off air supply

B.  increasing the surface tension of water and larvae sink

C.  reducing the surface tension of water and the larvae sink.

D.   reducing the density of water and the larvae sink

11.

The above figure shows a child on a swing . The child will have

A.  maximum potential energy at P and R B.  maximum potential energy at Q

C.   maximum kinetic energy at P D.   no kinetic energy at Q

12.   When an unknown particle X is used to bombard a lithium atom, two alpha particles are produced according to the equation 73Li + X 42He + 42He X is

A.  a beta particle B.  an alpha particle

C.  a neutron D.  a proton

13.

The diagram in the figure above shows a beam of electrons directed to pass between the poles of a magnet. The electron beam would be

A.  deflected towards the South Pole  B.  deflected downwards

C.  slowed down D.   reflected backwards

14.   The pitch of a note from a guitar string can be made higher by

A.  lengthening the string

B.  tightening the string

C.  heating the string

D.  increasing the thickness of the string

15.  The power used in a 100Ω resistor connected to 12V source of emf is

A.   0.69W B.  1.20W C.  1.44W  D.   8.33W

16.

The system of glass tubes in the above figure is filled with water placed upright with LM above KN and heated at X. The water is most likely to flow from

A.   L to K B.  K to N C.  N to L   D.   M to N

17.   An aeroplane of mass 5000kg moves with an initial velocity of 10ms-1 on the run-way. It then accelerates at 4ms-2 for 25s before it takes off. Calculate the change in momentum before take off.

A.  2.5×105  B.  3.0×105 C.  5.0×105 D.  5.5×105

18.  12080X is the symbol for a nuclide whose atomic number is

A.  40 B.  80 C.  120 D.  200

19.

The above diagram represents a velocity-time graph for the motion of a body. Calculate the distance the body covers in 8s

A.  50m B.  80m C.  100m D.  160m

20.   Which one of the following circuits is recommended for wiring electric lamps in a house

A.  A B.  B C.  C D.  D

21.   The main function of a step-up transformer is to

A.   increase current  B.  increase voltage

C.  increase resistance  D.   change a.c to d.c

22.  The stability of a bus is reduced when a heavy load is placed on its root rack because

A.  the total weight is increased

B.  the pressure upon the tyres is increased

C.  the maximum speed is reduced

D.  the centre of gravity is raised

23.

An iron barometer XY was placed on the middle of permanent bar magnet as shown in the diagram above. The iron bar was later found to have acquired magnetism temporarily. Which of the following would be the possible induced polarities?

INDUCED POLARITIES

X   Y

A.  North  North

B.  North  South

C.  South  North

D.  South  South

24.   If forces acting on a train moving along a level straight track are equal and opposite, the train will

A .  Come to a stop B.   accelerate uniformly

1.  move with a faster speed  D.  move with a constant speed

25.  Which of the following graphs shows how the extension of a spring varies with the force stretching it?

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26.

The block and tackle pulley system in the above figure has an efficiency of 80%. The load which can be lifted by an effort of 10N is

A.  4N B.  8N C.  40N D.  50N

27.  Which of the following represents the firing order of 4 stroke petro engine?

A.  exhaust ,inlet , compression and power strokes

B.  inlet, power, compression and exhaust strokes

C.  power, compression, inlet and exhaust strikes

D.  inlet, power, exhaust and compression strokes

28.  A current of 0.5A flows when an electric lamp is connected to a battery of emf 12V . What is the total resistance in the circuit?

A.  0.042Ω B.   6.0Ω C.  12.5Ω D.   24.0Ω

29.  A machine which is 80% efficient is run by an engine with an out put of 40W. The time taken to raise a load of 1500N through 0.15m will be

A.   4.5s B.   5.6s C.   7.0s D.  28.1s

30.

Two weights are balanced on a rule of negligible mass as shown above. What is the value of W?

A.  2.5N B.  10N C.  30N D.  40N

31.   Which one of the following statements in the table below correctly shows how both the boiling point and freezing point of water are affected by salt dissolved in the water ?

 Freezing point Boiling point A rises rises B rises decreases C decreases rises D decreases rises

32.   The image of a distant object formed by a pinhol

(i)  Real   (ii)   diminished (iii)   erect

A.  (i) only B.   (i) and (ii) only  C.  (ii) and (iii) only  D.   (i) ,(ii) and (iii)

33.   When a liquid is heated

A.   its density decreases

B.   boiling occurs at all temperatures

C.   its molecules move with the same speed

D.   evaporation takes place throughout the liquid

34.   Sound waves

A.   do not pass through a vacuum B.  travel through solids than in air

C.  do not travel through liquids  D.  travel at the highest speed in air

35.

In the circuit diagram in the figure above, the ammeter reading is 0.2A. The reading in volts shown by the voltmeter is

A.   6 B.   8 C.  10 D.  12

36.   In an experiment to find how the force of repulsion between two magnets varies with their distance apart, the following results were obtained

 Force (N) 3  12 48 300 Distance. d(m) 1.0  0.50  0.25  0.10

From the results, it can be deduced that

A.   F α d2 B.   F α d C.  F α 1/d D.  F α1/α2

In each of the questions 37–40, one or more of the answers given may be correct. Read each question carefully and then indicate on your answer sheet according to the following

A. if 1,2,3 only are correct B. if only 1,3 are correct C. if 2,4 only are correct

D. if 4 only is correct

37.   Which one of the following statements are correct about the resistance of a metal wire

1.   It increases with the length of the wire

2.  It increases with the cross-sectional area of the wire

3.  It depends in the material of the wire

4.  It decreases with the temperature of the wire

38.  The difference between x-rays and ultraviolet rays is that x-rays have

1.   A greater velocity 2.  A shorter wave length

3.   A lower frequency 4.  More energy

39.   Which of the following statements are true abut the action of a curved mirror on rays of light

1.   Rays incident to the pole make the same angle with the principal axis after reflection

2.  Rays passing through the focal point are reflected back along the same paths

3.  Rays incident parallel to the principal axis are reflected through the principal focus

4.  Rays passing through the centre of curvature are reflected parallel to the principal axis

40.  The particles of the medium through which a transverse wave tr4avels

1.  Remain stationary

2.   Move along with the wave.

3.   Move counter to the wave

4.   Vibrate perpendicular to the direction of the wave

SECTION B 1991

1.

A source of emf of 14V is connected as shown in the above figure . If R1= R2=R3=R4=R5=1Ω, find

(i)  The equivalent resistance of the circuit

(ii)   the current flowing through R5.

(iii)  The current through R3

2.   A particle initially at rest falls under gravitational force

(a)  (i)  Sketch a velocity-time graph for the motion.

(ii)  Calculate the total distance traveled after 5s

(b)   Sketch a displacement-time graph for the motion

(c)  Draw the acceleration-tome graph for the motion

3.  The figure below shows a circuit diagram of a part of a wiring system of a car. H1 and H2 are headlamps and P1,P2,P3and P4 are parking lamps

(a)  How can

(i)  All the lamps be switched on

(ii)  both headlamps be switched off without affecting the parking lamps

(b)  State what happens to the lamps if P1 is broken when the lamps are all on. Give a reason for your answer

4.

The diagram above shows two identical sources S1and S2 emitting waves in a ripple-tank.

(a)  (i)  Draw on the diagram lines connecting pressure where the water surface is most

disturbed

(ii)  How are the points in (i) formed

(b)   What property of waves is illustrated in the above diagram

5.  (a)  A ticker-timer vibrates at a frequency of 40Hz. The distance between two consecutive

dots is  2cm. Find

(i)  The time that elapses between two consecutive dots.

(ii)  The average speed of the tape

(b)  Using the ticker-timer in (a), the tape dots shown in the figure below were obtained

Calculate the acceleration of the tape. Assume that the ape was pulled at a constant acceleration.

6.  (a)  Two curved mirrors P and Q each of focal length 23cm apart as shown in the figure. An

object OA is placed 5cm from P and on the comm0n principal axis.

By graphical method, find the distance between the images formed by the two mirrors

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(b)  What would be the distance between the images in A if P and Q were plain mirrors

7.  (a)  State Archimedes principle

(b)  A glass block weighs 25N in air. When wholly immersed in water, the block weighs15N. Calculate

(i)  the up thrust on the block.

(ii)  The density of the glass in kgm-3

8.  (a)  What is meant by half-life of radioactive nuclei?

(b)  146C is a radioactive nuclide with a half life of 5600years and decays by emitting β particles

(i)   Write a balanced equation for the decay (ii) A carbon source initially contains 8×106 atoms. Calculate the time taken for 7.75×106atoms to decay

9.   The diagram in the figure below shows the structure of a bridge

(a)  Name the type pf force that acts along the side 1,2,3 and 4 when the bridge has a load at the centre

Side force

1…………………………………………………………………..……………..

2………………………………………………………………………………….

3………………………………………………………………………………….

4 ………………………………………………………………………………….

(b)  Name one material in each case that can be used to construct parts 2 and 4. Give one reason for your answer in each case

10.  (a)

A graduated glass tube containing air trapped below a mercury thread is immersed in a beaker of water and the water is heated as shown in the figure above

(i)  Sketch a graph showing how the volume of the trapped air varies with absolute temperature

(ii)  When the temperature of the water is 270C, the volume of the trapped air is 1.2×10-1cm3. Calculate the volume of air when its temperature is 770C.

(b)  How can the glass tube in (a) be used to find the temperature of a freezing mixture of ice and salt

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