1.
The energy in a mechanical system is determined by adding the potential and kinetic energy together.

total
massive
2.
The initial energy is equal to zero because the starting point is set at zero height to make things easier.

kinetic
potential
3.
In the example, the final kinetic energy is determined to be because at the peak height, the ball instantaneously stops.

positive
zero
negative
4.
In this system, potential and kinetic energy are proportional.

inversely
directly