Question

A boy is on a 78.4m high cliff drops a stone. One second later , he throws another stone downward with same speed. The two stones reach the ground simultaneously. Find the speed with which the second stone was thrown. (Acceleration due to gravity=9.8 m/s2

Answer 1

v=d/t

v=78.4/x m/s

a=v/t

9.8=(78.4/x)/x

9.8=78.4/x^2

x^2=8

/(x^2=/(8

x=2.83 s

v=78.4/1.83

v=42.9 m/s