Conservation of energy and momentum

Everything fits those requirements if you think hard enough about the connections.

 

Generally, one would use energy to describe two occurrences that are separated by distance, while moment would apply to two occurrences that are separated by time if that makes sense.

For instance, when considering the amount of energy converted by a single generator in an impoundment hydroelectric facility one would: 1. develop an equation for the mass of water (vol x density) and use it to determine the potential energy of a volume of water entering the penstock. 2. use the PE to find the kinetic energy at the outlet of the penstock (being careful to account for the fact that the penstock is at an angle). 3. use KE to find energy imparted to the generator. obviously, this is an over-simplified example but i think it will help.

Momentum, on the other hand, would be used to solve such problems as: a billiard ball has mass m and moves with a velocity v and hits the object ball at an angle of 30 degrees, what is the velocity of the object ball after the collision?