VCE · Topic explainer
What is elastic potential energy?
Elastic potential energy is energy stored when an object is deformed elastically. For a spring that obeys Hooke’s law, the energy stored relative to its natural length is E = ½kx². Here k is the spring constant and x is the extension or compression in metres.
Worked example
An ideal spring has a spring constant of 160 N/m and is stretched 0.15 m from its natural length. The applied force increases from zero to 24 N as it stretches. The work done is the area of the triangle under the force–extension graph.
The energy stored is ½ × 160 × 0.15² = 1.8 J. Stretching the same ideal spring twice as far stores four times as much energy, provided the spring still obeys Hooke’s law.
Official exam practice
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