We are going to talk a little bit about power tomorrow, so today we will have a small introduction to the subject by introducing motion.

Velocity is speed, mass is weight, and both apply to inertia. Inertia is the opposition to change in motion. The Law of Inertia states: An object at rest or in motion tends to stay at rest or in motion until an outside force acts on it.

Momentum (kinetic energy) is the energy within a moving object. Momentum is mass multiplied by velocity (or, weight x speed)

An example of momentum would be an 80 pound weight being dropped from a roof top. Sure, you may  be able to pick up an 80 pound weight with your arms, but would you try and stop it from hitting the ground if it was dropped from a roof top? The momentum of the weight would make it difficult to stop… that is what the Law of Inertia is trying to say: now that the weight is in motion, it wants to stay in motion until an outside force, such as the ground, stops its motion.