Q12 of 15 Page 299

Give reasons for the following:

(a) A ball thrown upwards in a running train returns back to the hands.


(b) When a person moves out of a boat, it moves backward.

Reasons:–

a) . This is due to the inertia of motion which is that the body in motion likes to stay in motion and resist and change in its state.


b) This is due to the Newtons third law of motion.


As the man is trying to push himself forward, he is simultaneously pushing the boat back.


More from this chapter

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10

A body at rest opposes the force which tries to move it. Name this property and give two examples to illustrate it.

 11

Observe the following v-t graphs and explain the type of force acting in the cases given:

 13

(a) Write an activity to demonstrate balanced and unbalanced forces.

(b) State whether the forces are balanced or unbalanced in each case:


(i) Suitcase dropped from a height.


(ii) A bicycle moving with constant velocity on a straight road.


(iii) The rope does not move in a tug of war on applying force at both ends.

 14

State and prove the law of conservation of linear momentum.