### SECTION A (25 Marks)

Answer all the questions in the spaces provided.
1.

2 marks

2.

1 marks

3.

The 10kg√ one, hot air containing CO2 rises from the short to the long candle extinguishing it. √

2 marks

4.

Becomes less stable. √When the water freezes it expands raising the position of centre of gravity.

3 marks

5.

3 marks

6.

They move towards each other/closer. √ The blown air increases the speed of the air between them. This reduces pressure√ between and external pressure/atmospheric pressure pushes them together.

2 marks

7.

Surface tension pulls the film inside as it tries to get the smallest surface area. √

3 marks

8.

– Force pump can raise liquid to any height unlike lift pumps which are restricted by atmospheric pressure. √

- Force pump delivers liquid in both up and down strokes while lift up pump delivers liquid on up stroke

- Force pump delivers liquid continuously while lift pump delivers it at intervals√.

2 marks

9.

The air particles are in the constant random motion, they collide with the walls √and their change in momentum per unit time/rate of collision causes pressure.

2 marks

10.

The heat energy is used to break the bonds/intermolecular forces√ holding the liquid particles together

1 marks

11.

A, √it has less number of turns hence less stiffer. √

2 marks

12.

Sum of clockwise moments = Sum of anticlockwise moments

2 marks

13.

It increases/lengthens the time√ of impact hence reducing velocity impulse.

1 marks

14.

The body is moving with an increasing non-uniform acceleration. √

2 marks

### SECTION B (55 Marks)

Answer all the questions in this section in the spaces provided.
15.

a) Heat, sound, light, chemical, potential ,kinetic e.t.c√

b) i) work done = force x distance√

= 20,000 x 3.0 = 60,000 J √

11 marks

16.

a) The velocity reduces/decreases with time.

c) i) Gravitational force of the earth. √
ii) Towards the centre of the earth. √
iii) I. –√
= – x 3
ii. Tension = mw2r – mg√

8 marks

17.

a) i) 220C√

ii) - Some heat lost due to poor thermal contact√

- Some is used to heat/heating up of the oil of the immersion heater. √

iii) The heating element remained hot Lime continuity to heat the block. √

iv) Heat lost = heat gained

MC∆Ѳ = Vlt

2kg x C x (52-30) = 22 x 10 x (5-2) x 60

b) – Some heat energy is lost due to poor lagging

- Poor contact and in raising the internal energy the particles in the solid.

8 marks

18.

a) Provided there is no external force acting on a system of colliding bodies the sum of momentum of the system remains constant.
b)

i) co-efficient of friction µ = 7f/mg√

c) Backward forces were greater than the forward forces since water surface posses less

10 marks

19.

b) – Density has units relative density has no units

- Relative density compares or is the number of times a substance is denser than water while density mass per unit of volume of a substance.

10 marks

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