Potential energy of a spring
The elastic potential energy stored in a spring can easily be obtained. K is the spring constant, x the amount of length the spring is stretched or squeezed: Potential energy in a spring U0 is the stored energy in a spring when it is unstressed; this always equals zero. So this is the formula for the potential energy in a spring: Potential energy in a spring
Example
Consider a spring with a spring constant of 30 N/m which has a lengt of 20 cm in it's equilibrium position. A force causes the spring to increase to a length of 35 cm. The potential energy stored in the spring can be calculated; Example energy in a spring
Torsion spring
The energy stored in a torsion spring can be calculated with a similar formula: Energy in a torsion spring Variable θ is the angle of twist in radians, κ is the spring constant with units of Nm/rad. Sometimes it is called the spring's torsion coefficient or torsion elastic modulus.