# Momentum

Momentum is a vector describing a "quantity of motion"
or in mathematical terms p (momentum) = mass (m) times velocity (v).

p=mv

## Conservation of Momentum

In a closed system, such as when two objects collide, the total momentum remains the same, though some may transfer from one object to the other. Momentum is always conserved in a closed system, but most sporting situations in the real world are not a closed system. For example, when a baseball bat hits the ball, the ball will be squished to a certain degree. After few milliseconds, it rebounds back. This contraction and rebound action is causes the release of heat energy, and some momentum is lost, or transferred elsewhere.

## Maximizing Momentum

As momentum is the product of mass and the velocity, you can increase momentum by increase either of these elements. In sport, examples include using a heavier bat or racket and increasing running speed or hand speed.

## Angular Momentum

Angular momentum is the product of Moment of Inertia and Angular Velocity. Moment of Inertia is the angular counterpart to mass - it is the measure of the resistance of an object to changing its angular speed.

A good example of angular momentum in action is with figure skaters. A figure skater starts a spin by pulling in his arms to lessen his Moment of Inertia. By the Conservation of Momentum Principles, the angular speed must then increase. To come out of the spin, a skater simply extends her arms to increase angular momentum and decrease angular velocity.