# Homework Help: Springs, Energy, Work (simple question)

1. Mar 14, 2006

### jcais

1. Is work of a spring the same as the potential energy of a spring? U = .5kx^2?

2. Do springs have a kinetic energy formula? If so, what is it?

3. Work is the same as energy right? Because work and energy are both in joules, right?

work = fdcostheta = kgm^2/s^2 = newton meter = joule
energy:
kinetic energy = 1/2mv^2 = kgm^2/s^2 = newton meter = joule
potential energy = mgh = kgm/s^2m = newton meter = joule

Thank you for your help.

2. Mar 14, 2006

### kant

1)

no. a postive change in work, is equal to a negative change in potential energy.

2) i dont think you need to know it yet.

3) Well, everything you have a change is the energy state, there should be some work involud in the process to make it so.

3. Mar 14, 2006

### Galileo

The phrase "work of a spring" makes no sense. You can only speak of the work done ON an object (by some force) when it is moved from point A to point B. What you mean is: Is the work done on an object tied to the spring when moved from the equilibrium position to a distance x away from equilibrium by some external force equal to the final potential energy stored in the spring, 1/2kx^2? Then yes.

The spring is usually massless to make things simple, so no, the spring doesn't have kinetic energy. The object attached to the spring however has kinetic energy equal to 1/2mv^2, that always holds.

Work and energy have the same units, but they are quite different concepts. A relation between them is given by the Work-Energy theorem.