What is the Potential Energy of a Twisted Spiral Spring?

[Sumbhajee]

Homework Statement

A spiral spring is twisted from its equilibrium position through θ = 7° by an average torque of 60 Nm. What is its potential energy in Joules?
http://schubert.tmcc.edu/res/msu/mmp/kap8/picts/spring2.gif

Homework Equations

The Attempt at a Solution

I am not even sure how this is possible without the spring constant.. Any help would be greatly appreciated.

 

[willem2]

You know the torque and how much the string is twisted. Surely you can find the spring constant?

 

[mikelepore]

In linear motion problems we have a formula for work in terms of force and displacement. You need to find the formula that is analogous to this but used for rotational motion.