# How do you calculate the energy stored in a power spring?

1. Jan 13, 2014

### Webbd050

How do you calculate the energy stored in a power spring? For a uni project one of my concepts is a KERS which stores the cars kinetic energy in a power spring. under braking a shaft connected to the cars drive train is engaged which is connected to a few power springs as shown here http://www.spiroflex.com/pdfs/Mtr_spr_A_B_eng.pdf when the shaft rotates it coils the springs around it. How can i calculate the energy stored and torque output?

2. Jan 13, 2014

### Staff: Mentor

Since this is your schoolwork project, you need to tell us about your thoughts, before we can be of much tutorial help.

What is the traditional equation for the energy stored in a spring? How is that different or modified for the spring geometry you are asking about?

3. Jan 13, 2014

### Webbd050

Its for university not school hahaha. Well a standard spring is either compression or extension a power spring is rotational. The equation for a standard spring is PE= 1/2 k x^2 which i suppose could be used im just unsure of how to work out the spring constant.