# Work done by spring with weight to the spring

1. Nov 19, 2009

### NoBodyKnows

Hey, I just have a quick question. I understand that the work done by a spring is considered as the following; Ws=-.5kx^2. What if the spring has weight to it? Would the work done by the spring be Ws=-(.5kx^2)-m(spring)g? Does the weight get added or is it not even considered in that equation?

Cheers!

*i'm saying the weight is the spring, I understand where the weight the spring is holding is associated but what about the mass of the spring if there is one

2. Nov 19, 2009

### PhanthomJay

In the absence of more data, about all you can say about the work done by a spring that is not massless is, since both spring and gravity forces are conservative,
$$W_s + W_g = - (\Delta U_s + \Delta U_g)$$. If the spring was horizontal, its mass wouldn't matter, but the case would be different if the spring was vertically mounted.