FORM 2 CHAPTER 7 DYNAMICS

NAME :_________________ 05/09/2015 SATURDAY

1. (a) Name the forces shown in Diagram 1.1.

[4 marks]

(b) Diagram 1.2 shows a girl playing hockey.

State two effects of force on the ball when the girl hits the ball with a hockey stick.

(i) …………………………………………………………………………………………………….

(ii) …………………………………………………………………………………………………….

[2 marks]

1

Diagram 1.2

(i) …………………………………..

(ii) …………………………………..

(iii) …………………………………..

(iv) …………………………………..

Diagram 1.1

2. A worker pushes a sack of rice using a trolley to the shop as shown in Diagram 2.1.

(a) If the frictional force between the trolley and the ground is 500 N, calculate the work done by the worker.

[2 marks]

(b) A boy tries to push the sack of rice but the sack is too heavy for him to move.

(i) Did the small boy do any work?

………………………………………………………………………………………………….[1 mark]

(ii) Why?

………………………………………………………………………………………………….[1 mark]

(c) The worker carries a sack of rice weighing 50 kg upstairs. If the mass of the man is 65 kg, calculate the work done in Diagram2.2.

(1 kg = 10 N)[2 marks]

2

Diagram 2.1

Diagram 2.2

(d) The worker takes 5 minutes to complete the work in (c). Calculate his power.

[2 marks]

3. Diagram 3.1 shows a wooden block being pulled on a table top.

(a) Name the forces acting on the wooden block.

(i) …………………………………………………………………………………………………

(ii) …………………………………………………………………………………………………

[2 marks]

(b) Using , draw the direction of the frictional force acting on the wooden block in the box provided in Diagram 3.1.

[1 mark]

(c) What will happen to the reading of the spring balance if the same wooden block is pulled along a piece of sand paper?

………………………………………………………………………………………………………

[1 mark](d) Diagram 3.2 shows a man pushing a box towards the wall.

3

Wooden block

Smooth table top

Spring balance

Diagram 3.1

Wall

Box

5 m

Diagram 3.2

(i) Suggest one way on how he can reduce the force needed to push the box.

…………………………………………………………………………………………………..

[1 mark]

(ii) If the force needed to push the box is 300 N. Calculate the work done by the man in pushing the box towards the wall.

[2 marks]

4. Diagram 4.1 shows some methods used to reduce friction.

(a) Name method P, Q, and R on Diagram 4.1.

[3 marks]

(b) Diagram 4.2 shows some used tyres.

4

P: ……………………….. Q :………………………. ………………………..

R ………………………..

Diagram 4.1

Diagram 4.2

(i) What has happened to the surfaces of the tyres?

………………………………………………………………………………………………….

[1 mark]

(ii) Explain your answer in (b)(i).

…………………………………………………………………………………………………….

…………………………………………………………………………………………………….

[1 mark]

(c) Diagram 4.3 shows two persons walking.

(i) State one advantage of friction in this situation.

…………………………………………………………………………………………………

[1 mark]

(ii) State one disadvantage of friction in this situation.

…………………………………………………………………………………………………

[1 mark]

5

Diagram 4.3