Question

A child throw a ball upward and catch it again after 8 second then find the velocity which it thrown

Answer 1

v = u+at

In the case of the upward journey,

v = 0 m/s, a = -10 m/s^2 and since the time of both the upward and downward journies is the same so t for upward journey = t for downward journey = 8/2 = 4s.

as per the above mentioned equation

0 = u - 10 x 4

0 = u - 40

u = 40m/s