Question

a stone is dropped from the roof of building it take 4second to reach the ground find height of builiding

Answer 1

S= ut + 1/2 gt^2 where S= distance, U = initial velocity, t= time and g= acceleration due to gravity.  

Given: U=0 m/sec, t= 4sec.  

we know g= 9.m/sec^2  

Therefore, S= 1/2gt^2  

or, s= 1/2 *9.8 *16  

or, S= 78.4 meter.