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# KCSE Physics Paper 1 – 2015 KCSE Ikutha Sub-County Joint Examination

## KCSE Physics Paper 1 – 2015 KCSE Ikutha Sub-County Joint Examination

### SECTION A (25 Marks)

Answer ALL the questions in this section in the spaces provided.

1.

The figure 1 below shows a measuring cylinder with a fluid to the level shown.

Find the new level when a solid of mass 13.6g and a density 1250kgm3
is fully immersed into the cylinder.

2 marks

2.

State two factors that affect surface tension.
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2 marks

3.

Explain why the handle of a door is usually placed as far as possible from the hinges.
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1 marks

4.

A tin with a hole is filled with water to a certain height. Water jets out as shown in figure 2(a) below. A
second identical tin is filled with water to the same height and a block of wood floated as shown in
figure 2(b).

State the reason why the maximum distance of jet d2 is greater than d1.
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1 marks

5.

Sketch a displacement time – graph for a body which is uniformly accelerated.

2 marks

6.

A horse rider bends forward when the horse is on high speed. State a reason for this observation.
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1 marks

7.

Figure 3 below shows energy transformation chain of a lighting system of a bicycle.

Name the transducers A and B.
A ___________________________________________ (1 mark)
B ___________________________________________ (1 mark)

2 marks

8.

Figure 4 below shows a uniform metre rule of mass 300g pivoted at the 0 mark and kept balanced
horizontally by a string fixed at 55cm mark.

Determine the tension in the string.

3 marks

9.

The figure 5 shows identical wooden splinters burning. One is placed on wood and the other on metal
block. When the flame reached the edge of the metal block, the splinter went off but the one on wood
continued burning. Explain.

2 marks

10.

State the difference between evaporation and boiling.
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2 marks

11.

Three springs shown below are identical and of negligible weight. The extension produced on the
system is 20cm.

Determine the constant of each spring.

3 marks

12.

State two factors that affect the critical velocity of a vehicle negotiating a bend.
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2 marks

13.

Figure 7 represents a garden sprinkler.

On the same figure indicate the direction of rotation of the sprinkler when water is ejected through the nozzles at a high velocity.

1 marks

14.

State the principle of conservation of energy.
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1 marks

### SECTION B (55 Marks)

Answer ALL the questions in this section in the spaces provided.

15.

a) A boy throws a tennis ball vertically upwards from a truck moving at a constant velocity.
Give the reason why the ball lands back exactly the same point where it was projected. (1 mark)
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b) Define impulse in terms of momentum. (1 mark)
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c) A trailer of mass 30 tonnes travelling at a velocity of 72km/h runs onto a stationary bus of mass 10
tonnes. The impact takes 0.5seconds before the two vehicles move off together at a constant
velocity for 15 seconds. Determine,
i) The common velocity. (3 marks)
ii) The distance moved after the impact. (2 marks)
iii) The impulsive force on the trailer on impact. (3 marks)
d) Give a reason why when a passenger jumps from a floating boat, the boat moves backwards.
(1 mark)
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e) Give the reason why a safety seat belt used in a vehicle:
i) Should have a wide surface area. (1 mark)
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ii) Should be slightly extensible. (1 mark)
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13 marks

16.

a) State two ways through which the rate of evaporation of a liquid may be increased. (2 marks)
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b) A metal of 10kg is heated to 1200C and then dropped into 2kg of water. The final temperature of the
mixture is found to be 500C. Calculate the initial temperature of the water
(Specific heat capacity of metal = 450Jkg-1K-1
and specific heat capacity of water = 4200Jkg-1K-1)(3 marks)
c) Give the property of water which makes it suitable for use as a coolant in machines. (1 mark)
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d) Formation of ice on roads during winter in cold countries is known to hamper vehicles.
State two ways in which the melting point of ice may be lowered to solve this problem. (2 marks)
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e) Some ether is put in a combustion tube and two glass tubes inserted into the tube through a cork as shown in the figure 8. The combustion tube is then put into a smaller beaker containing some water and a thermometer dipped in the water. When air is blown into the ether as shown, the reading in the thermometer lowers. Explain this observation. (2 marks)

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10 marks

17.

a) Figure 9 below shows a machine being used to raise a load. Use the information given in the figure to answer questions below.

i) Determine the velocity ratio of the machine. (1 mark)

ii) If a load of 800N is raised by applying an effort of 272N, determine the efficiency of the
machine (3 marks)
b) A crane lifts a load of 2000kg through a vertical distance of 3.0m in six seconds. Determine:
i) The work done. (2 marks)
ii) The power of the crane. (2 marks)
c) State two reasons why the efficiency of a machine is not 100%. (2 marks)
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d) A block of a metal having a mass of 40kg requires a horizontal force of 100N to drag it with uniform
velocity along a horizontal surface. Determine its coefficient of friction. (3 marks)

13 marks

18.

Figure 10 below shows the same block weighed in air, water and liquid. Given that the reading of the
level of water becomes 150cm3 when the metal is fully immersed.

a) Determine:
i) The density of the metal. (3 marks)
ii) Water level before the solid was immersed. (3 marks)
iii) The density of the liquid L. (3 marks)

b) A certain mass of hydrogen gas occupies a volume of 2.6m3 at a pressure 1.5 × 105 pa and temperature of 12oC. Determine its volume at a temperature 0oC and pressure of 1.0 × 105 pa. (3 marks)

12 marks

19.

a) A bullet is fired horizontally at a velocity of 400ms from a cliff which is 50m tall as shown in
figure 11 below.

i) On the diagram draw the trajectory of the bullet until it comes to rest. (1 mark)
ii) Find the time taken for the bullet to hit the ground. (2 marks)
iii) Find the range of the bullet. (1 mark)

b) i) An electron of mass 9.1×10-31 kg is spinning around an atom of radius 6.2×10-11 m at a speed
of 3.0 × 108ms-1. Determine the force acting on the electron. (2 marks)

ii) If the electrostatic force on the electron was suddenly removed, how will the electron move?
(1 mark)
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7 marks