Question

a man throws a ball vertically upwards with a velocity of 20 m /s-2 . After what time will the ball come back to his hands
plz ​

Answer 1

Correct question:-

A man throws a ball vertically upwards with a velocity of 20m/s. After what time the ball will come back to his hands.

Given:-

→Initial velocity of the ball=20m/s

To find:-

→Time taken by the ball to come back to his hands

Solution:-

In this problem we will take g=10m/s²,to make our calculations easier.

For upward journey of the ball:-

•Acceleration due to gravity will be -10m/s²,as the ball is going against gravity

•Velocity of the ball at the highest point will be zero,thus v=0.

By using the 1st equation of motion,we get:-

=>v=u+gt

=>0=20+(-10)t

=>-20= -10t

=>t= -20/-10

=>t=2s

Here,we can see that the ball takes 2s to reach maximum height. So,the ball will take same time from max.height to return to the thrower as we know that:-

=>Time of ascent=Time of descent

Thus,total time taken by the ball to reach the hands of the thrower :-

=>(2+2)s

=>4s

Hence,the ball takes 4 seconds to come back to the hands of the man.