The boy gives the ball some kinetic energy when he throws it, and
the ball swaps its kinetic energy for gravitational potential energy
until it runs out of KE.
The KE of the ball when it leaves the boy's hand is
(1/2) (mass) (speed)²
= (0.095 kg) (21.5 m/s)²
= (0.095 kg) (462.25 m²/s²)
= 43.914 joules (rounded)
The ball keeps rising until it has swapped all of those joules
for potential energy. Then it stops rising and begins to fall.
