Elastic potential energy is the energy stored in a spring when work is done on the spring to compress or stretch it.
The variable 'x' is the change in the length of the spring (how much it stretches or squishes. The variable 'k' is the stiffness of the spring and is a property of the material that spring is made of.
The variable 'x' is the change in the length of the spring (how much it stretches or squishes. The variable 'k' is the stiffness of the spring and is a property of the material that spring is made of.