Question

A ball is thrown vertically upwards. It goes to a height 20m and then returns to the ground. Taking acceleration due to gravity g to be 10m/s^2, find:
1) the initial velocity of the ball.
2) the final velocity of the ball on reaching the ground
3) the total time of journey of the ball


[ show me the process please.
answers given 1) 20m/s 2) 20m/s 3) 4s]​

Answer 1

Answer:

a) The initial velocity of the ball is 20m/s :

As it reaches a maximum height of 20m

and the acceleration is 10m/s^2.

So in order to reach a height of 20m ,with an acc. in opp. direction it has to move with 20m/s

b) 20m/s

As the velocity of any object thrown upward with some speed lands on the ground with the sane speed

c) use v=u+at

0=20-10t

»t=2 sec

but this is the time it reach the max. height

so it will take 2 more sec to reach ground

» Time = 4 sec

hope...it...helps..

Answer 2

Explanation:

1) at highest point velocity of ball is 0

so, v = 0

now, v^2 - u^2 = 2as

=> -u^2 = 2(10)(-20)

=> u = 20 m/s

2) same as first part

3) v = u + at

=> t = 2 sec

this time is for upward movement only

so, total time flight = 4sec

hope it helps uh......