Question

You serve a volleyball with a mass of 2.1 kg. The ball leaves your hand with a speed of 30m/s. The ball had kinetic energy. How do you calculate that?

Answer 1

Your best bet is to use the formula that describes the kinetic energy
of any moving object:

Kinetic Energy = (1/2) x (mass) x (speed-SQUARED)

In this question,
mass = 2.1 kg
speed = 30 m/s
speed² = 900 m²/s²

I have overwhelming confidence that you can take it
and finish it up from this point.