Question

stone of mass 15 that dropped from the top of building it takes 5 seconds to reach the ground find the height of building if g=10M/S2

Answer 1

As this is the case of free fall.

using eqn. of motion,
s = 1/2 a t^2

u is o
s is -s
a is -g

substitute values if a,t,g to calculate height of building.

Hope you get your answer.