Aball is thrown straight up from the edge of the roof of a building of height 60.0m. a second ball is dropped from the roof 2s later. what must be the initial speed of the first ball if both are to hit the ground at the same time?

u = 15.99 m/s

Explanation:

Given that

h= 60 m

For second ball

Lets take after t time after second ball hit the ground

Here u = 0 m/s

t=3.49 s

So the time taken by first ball will be 3.49 + 2 = 5.49 s

For first ball

u = 15.99 m/s

So the initial velocity of first ball will be 15.99 m/s

a longitudinal wave moves energy that is to the direction of the wave’s movement. - true