That is, the sums of the various momentums of the bodies before the collision are the same as momentums after the collision. Thus, we can frequently compute the velocities of vehicles before a collision by knowing their speeds and directions of travel after the impact. Momentum is not the same as, and should not be confused with, energy. When a force acts on a body, work is said to be done on that body. Energy is the capacity to do work.
Computations involving kinetic energy are tricky but informative.
Power is the rate at which work is done. When work is done at the rate of 33,000 ft-lbs. Its connection with equine work capacity is tenuous. A human being can apparently work at a rate of about .35 horsepower for short periods of time, if all their skeletal muscles are being effectively used. Thus, a body acted on by a 0.5 g acceleration experiences a force equal to half its weight.