Kinetic Work Energy Theorem

1. Mar 30, 2014

uestions

When does the Kinetic Work Energy Theorem not apply to a situation? Or better, is there a general form of the equation where work can equal the change in any energy? What is work besides a force and a distance?

2. Mar 31, 2014

TysonM8

The Work-Energy Theorem only applies to rigid bodies. That is, if the work is not used to deform the object.

There's a thread here that discusses this in detail;
http://physics.stackexchange.com/questions/58134/how-to-understand-the-work-energy-theorem

Work by definition, is what a force does on an object by displacing it. However, there are other ways of representing work if that's what you're asking.

Last edited: Mar 31, 2014
3. Mar 31, 2014

Staff: Mentor

Here's something that I wrote in another thread that may clarify how the "work"-energy theorem, when thought of as an application of Newton's 2nd law, may be applied to deformable bodies.

4. Mar 31, 2014

uestions

How can work be done to an object that has a change in potential energy, but no change in velocity?

5. Apr 1, 2014

Staff: Mentor

If the velocity doesn't change, the work-kinetic energy theorem just says that the net work must be zero. You do work when you lift an object at constant speed, but gravity is also doing negative work.