D. Answer the following questions in brief.
1.
In the following situations, identify the agent exerting the force. Also, state
the effect of the force in each case.
(a) Squeezing a piece of lemon between the fingers to extract its juice.
(b) A person diving into a swimming pool.
(c) A labourer moving a loaded cart.
(d) A car coming to rest once its engine is switched off.
(e) An athelete making a high jump to clear a bar kept at a certain height.
2.
An object experiences a net non-zero force. Is it possible for the object to
move with a constant speed along a straight line?
3.
Distinguish between:
(a) balanced and unbalanced forces.
(b) contact and non-contact forces.
Answers
Explanation:
(a) In squeezing a piece of lemon, force responsible is muscular force which changes the shape of the lemon and the agent exerting the force is fingers.
(b) In taking out paste from a tube the force changes the shape of the tube and the agent exerting the force are the hands or fingers.
(c) In suspending a load from a spring while other end is on a hook fixed, the force changes the shape of the spring and the agent exerting the force is the load.
(d) In the high jump by the athlete the force acts on the ground and the ground helps the athlete in jumping. The effect os change in motion and the cause id muscular force or friction force.
2) When a net zero external unbalanced force is applied on the body, it is possible for the object to be travelling with non-zero velocity.
In fact , once an object comes into motion & there is a condition in which is imposed by any external force; the object will continue to remain m motion. It is necessary that the object moves at a constant velocity & in a particular direction.
3)
