# The Work-Energy Theorem

1. Mar 14, 2006

### jcais

Hello,

If the work changes the object's velocity through a horizontal distance then:

W = delta KE

But, what if the work changes the object's vertical position. Then the object's mph changes. Would the Work formula be:

W = delta PE?

But, if something is moving upwards (y axis) then it has both a change in PE and KE. What would the new equation be for total work? I'm confused because we are only taught the W = delta KE equation.

Thank you. :-)

2. Mar 14, 2006

### kant

Well, later in your textbook, or class, you will learn something call the conservation of mechincal( spell?) energy. which is:

W= delta E

where delta E is the sum of both delta PE , and delta KE plus.... others(but you don t need to know yet)

Since you know PE, then i assume you also know that work done by a conservative force is path independent. Using the same generialization, you can compute delta E once you know the initial , and final state of the thing you called: system.

Last edited: Mar 14, 2006
3. Mar 14, 2006

### Markjdb

It's generally more helpful to ignore seperate formulas and just remember that w = deltaME where ME is mechanical energy, and is, as kant said, the sum of kinetic and potential energy of an object in a system.

4. Mar 15, 2006

### jcais

this formula w = deltaME I will for sure write down

thank you all for your help :-)