a ball is dropped from rest at 25m above the ground. how fast is it moving at 10 m above the ground and b) how much time does it take to reach the ground? no air resistance.

1 answer

at ten meters it has dropped 15 meters
(1/2) m v^2 = m g h
v^2 = 2 * 9.81 * 15 = 294.3
v = 17.2 m/s at 10 m above ground

d = (1/2) g t^2
25 = 4.9 t^2
t = 2.26 seconds