Kinetic Energy
Whenever objects are in motion (velocity > 0)
there is energy produced due to its movement. This energy is called kinetic energy,
the energy of movement. And mathematically, kinetic energy is defined as:
K = (1/2)mv2
By inspection, we also notice that kinetic energy is the total momentum or momentum
is the rate of change of kinetic energy respect to velocity, v.
It is widely known that energy is neither created or destroyed. Mathematically speaking,
this simply means that the initial state of energy in a system is equal to its final state.
Ei = Ef
This statement also implies that if a ball slows down, its kinetic energy has been dissipated
into some other form however never "gone".
Sample Problem
A ball of mass m hits a smaller ball of mass m/4 at 4 km/s and comes to rest. What is the velocity of the smaller ball?
