Question

a ball thrown upwards in a running train return back to the hands.give reason

Answer 1

Dear student,

All the motion in the physics is relative to something called as the frame of reference. All our motion is compared with some frame of reference to understand it clearly.

For example,

Earth is moving around the sun, so that we all as well. suppose you are sitting somewhere. So when the earth is taken as the frame of reference, you are at stationary w.r.t. earth. but when sun is taken as the frame of reference you are in continous motion. So the relativity of motion will change depending upon the frame of reference.

Now coimng to our question,
a ball is thrown upwards in a running train. So taking train as the frame of reference, the person who threw the ball upward is at rest. (This is w.r.t. train, if the frame of reference is person standing outside the train, then the man who threw the ball will be in motion). The ball which is thrown in the air also at rest w.r.t. train. So the ball will return to hand.

Now if a person outside the train is obserbing the process, in his frame of reference of both the man and ball are moving. But the movement is constant So it will land directly in the hand.

Here the relative speed of man in the train and the ball thrown is zero w.r.t to the running train. So a kind of rest condition is felt in the object allowing only upward movement.