. A boy throws a ball of mass 2kg vertically into the air. The ball reaches a height of 3.2m,
(a) how long does it take the ball to reach the height? (b) how long
does it takes until it hits the ground? (C) at what speed does the
ball hit the ground

Since the (vertical) velocity of the ball is given by (assuming g≈ constant)

v(t)=dsdt=v0−gt,

the speed of the object when hits the ground is the velocity at time t∗, where t∗ is the value of t when s(t)=sG=0 (if your reference system is placed at s=sG=0 for the ground

Explanation:

I help

this is a good question! i'll do some research and come back when i have the answer!