power is the ability to get someone to do something he or she would not otherwise do” Work-Energy PrincipleThe change in the kinetic energy of an object is equal to the net work done on the object.This fact is referred to as the Work-Energy Principle and is often a very useful tool in mechanics problem solving. It is derivable from conservation of energy and the application of the relationships for work and energy, so it is not independent of the conservation laws. It is in fact a specific application of conservation of energy. However, there are so many mechanical problems which are solved efficiently by applying this principle that it merits separate attention as a working principle. For a straight-line collision, the net work done is equal to the average force of impact times the distance traveled during the impact.Average impact force x distance traveled = change in kinetic energyIf a moving object is stopped by a collision, extending the stopping distance will reduce the average impact force. Car crash example
| Seatbelt use
| Auto stopping distance
| Large truck-small truck collision
| Two trucks, equal momentum
| Impact force of falling object
| Work-energy principle for angular quantities
The rate of doing work is equal to the rate of using energy since the a force transfers one unit of energy when it does one unit of work. A horsepower is equal to 550 ft lb/s, and a kilowatt is 1000 watts.
| R Nave
| Go Back
Newton's law of universal gravitation states that every point mass in the universe attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. (Separately it was shown that large spherically symmetrical masses attract and are attracted as if all their mass were concentrated at their centers.) This is a general physical law derived from empirical observations by...
Please join StudyMode to read the full document