Question

Two balls are dropped from different heights at different instants. Second ball is dropped 2 seconds after the first ball. If both balls reach the ground simultaneously after 5 seconds of dropping the first ball, then the difference between the initial heights of the two balls will be? PLEASE EXPLAIN IN DETAIL.

Answer 1

the first ball be at height h1 and takes t1 time to knock the ground = 5 second

& in starting the second ball be at height h2 and takes t2 time to hit the ground = 5 -2 = 3 second

Equation of falling balls :

Distance  travelled by an ball falling for time = h = 1/2 gt^2

so h1 = 1/2 g(5)^2 = 25g/2

and h2 = 1/2 g(3)^2 = 9g/2

Diffrence in height = h1-h2

                              = 25g/2 - 9g/2 

                             = 16g/2 = 8g 

                             = 8 x 9.8 

                            = 78.4 m

& if uh take g = 10 m/s^2 then height will be 8 x 10 = 80m

i hope it will help you

regards