in ncert textbook of std. 8 in activity 11.3 it says first place a ball on table top or concrete floor and then push ball gently and when ball starts moving place palm in front of the moving ball. and as soon as ball touches your palm remove your palm. is force applied? in this i say that force is applied because speed of ball become slow but my teacher says that force isnt applied and i am not satisfied with my school teachers explanation please help me.

It''s funny how we have the same first name.

To the question,

Your teacher is correct.

This is because in this small moment of time when the ball touches the hand, the hand moves with the ball, thus the momentum becomes greater (due to a greater mass) but the force on the ball remains the same as the hand hasn''t applied any force on the ball.

An example might help here.

Suppose someone shoots a bullet at Rajnikanth, blatantly Rajnikant doesn''t die. But what he does is, he brings his hand in front where the bullet is coming, and starts running at the speed of the bullet. Obviously, Rajnikanth will feel the bullet but as long as you are moving with the bullet at the exact same speed, the force will not be transferred, thus teacher is right.

You should know that you are ufcourse right and your teacher sucks. As the given case follows the character of a force being applied. As the ball slows and thus force is applied but not enough to stop the ball but force acts and retard the ball.

exactly, that is my doubt i cant understand it, whenever i try that activity when the ball touches my palm its direction change along with speed i too try to remove hand as soon as possible. it doesnt happens like in rajnikanth''s case. i dont move my hand back like rajnikanth moves back when he gots bullet [and of course he will not get a scratch even when he will jump from aeroplane without parachute. ]