# Potential energy

1. Jul 29, 2009

### TooFastTim

Just reading up on lagrangeans and I came across an expression for potential energy I'd never seen before: V=(1/2)*m*w2*x2.

I suppose all you physics majors are familiar with it. But what is it and where can I find out more?

2. Jul 29, 2009

This looks like the equation giving the total energy of a system that moves with simple harmonic motion.

3. Jul 29, 2009

### flatmaster

4. Jul 29, 2009

### turin

It it not the total energy, it is, as the OP suggests, the potential energy. The total energy of the harmonic oscillator must also include the kinetic energy.

5. Jul 29, 2009

There is a continual interchange between PE and KE and the equation does give the total energy(ignoring damping).Expressing it another way it gives the maximum KE(when PE is zero) or the maximum PE(when KE is zero)

6. Jul 29, 2009

### turin

The expression gives the total energy only when the kinetic energy vanishes, at the turning points. Damping is irrelevant to the issue. Even if damping is present, the expression still gives the total mechanical energy of the harmoic oscillator when and only when the kinetic energy vanishes, at the turning points. In general, the expression does not give the total energy.

7. Jul 29, 2009