1.1.5 Elastic Potential Energy

• Elastic potential energy is the energy stored in an elastic object when work is done on the object.
• Elastic potential energy is stored in springs, rubber bands, and other objects that can change shape by stretching, bending or compressing.
• When a spring is stretched, work is done on the spring which results in energy being transferred to the elastic potential store of the spring.
• When the spring is released, energy is transferred away from its elastic potential store.
• The extension, e, of a stretched spring can be determined using the equation: e = ΔL/L0, where ΔL is the change in length and L0 is the initial length.
• The amount of elastic potential energy stored in a stretched spring can be calculated using the equation: Ee = ½ × k × e2, where k is the spring constant in newtons per metre (N/m) and e is the extension in metres (m).
• The elastic potential energy equation assumes that the spring has not been stretched beyond its limit of proportionality.
• A spring has been stretched beyond the limit of proportionality when the spring on the right is compared to the spring on the left.