Question

An apple hanging from a limb has potential energy because of its height . If it falls ,what becomes of this energy just before its hits the ground ? when it hits the ground?

Answer 1

Answer: Just before its hits the ground it becomes kinetic energy and when it hits the ground it becomes in another form of energy (acoustic energy or thermal energy, for example)

Explanation:

Energy is the ability of matter to produce work in the form of movement, light, heat, among others.

In this sense, according to the Conservation of Energy principle: "energy is not created or destroyed, it is transformed."

So, in the case of the apple, its total energy is conserved.

When the apple is hanging from a limb, it has zero kinetic energy $K_{o}=0$ (because it is at rest) and has gravitational potential energy $U_{o}$, which depends on the mass $m$, the acceleration due gravity $g$ and the height $h$:

$U_{o}=mgh$

When the apple falls, just before its hits the ground, this gravitational potential energy transforms in kinetic energy $K_{1}$ (since the apple is moving), which depends on the mass and velocity $V$ of the apple:

$K_{1}=\frac{1}{2}mV^{2}$

When the apple hits the ground, the gravitational potential energy is zero (h=0) and the kinetic energy transforms into some other form of energy (acoustic energy or thermal energy, for example).