Question

A stone is dropped from the top of a building reach the ground after 5 second. find the height of the tower

Answer 1

We have,
            u = 0 m/s
            t = 5 seconds
            a = 9.8 m/s^2
so, we know that,  v = u + at
                              => v = 0 + 49 = 49 m/s
Now,
        v^2 = u^2 + 2as
        => 49 ^2 = 0 + 19.6 s
        => 2401 = 19.6 s 
        => 122.5 m is the height of the building 
BUT IF YOU TAKE a= 10 m/s^2 THEN THE HEIGHT OF THE BUILDING WILL BE 125 METERS