We can solve this problem using the law of conservation of energy.
This law states that energy in a closed system must stay same.
That means that the energy of a ball leaving the hand and the energy of a ball when it reaches its maximum height must be the same.
The energy of a ball leaving the players hand is kinetic energy:
The energy when the ball reaches its maximum height ( and has zero velocity) is potential energy in a gravitational field:
As said before these energies must be the same, and that allows us to find the initial speed:
When we plug in all the number we get that
This law states that energy in a closed system must stay same.
That means that the energy of a ball leaving the hand and the energy of a ball when it reaches its maximum height must be the same.
The energy of a ball leaving the players hand is kinetic energy:
The energy when the ball reaches its maximum height ( and has zero velocity) is potential energy in a gravitational field:
As said before these energies must be the same, and that allows us to find the initial speed:
When we plug in all the number we get that