Question

A boy on a roof 180 m high, drops a stone. One second later he throws a second stone after the first. They both reach the ground at the same time. With what speed did he throw the second stone . (g = 10 m/sec2)​

Answer 1

Explanation:

s= ut+ 1/2a t²

u=0

so-180=1/2×10×t²

180=5t²

t=9.85

part 2 throwing stone t=1 sec less= 8.85

s=ut+1/2at²

where = 8.8u+5×8.8(approx)

-8. 8u=180-387

u=207/8.8

u=23.52km/per second(approx)