Elastic Potential Energy
What is Elastic Potential Energy?
Elastic potential energy is the energy stored inside an object when it is stretched, compressed, or twisted from its natural shape. When the object returns to its original shape, that stored energy is released.
Common examples:
A stretched rubber band before it’s let go.
A spring in a toy when it’s pushed down.
The trampoline fabric stretched under someone’s weight.
A bowstring pulled back before shooting an arrow.
Why is it Called “Potential” Energy?
The word potential means the energy is stored and waiting to be used.
When you pull back a bowstring, the bow doesn’t move yet – but the energy is stored, ready to be transformed into kinetic energy (movement) when you release it.
How Amount of Energy Changes
Two main factors affect the amount of elastic potential energy stored:
The material’s stiffness – measured by the spring constant (k) in units of N/m (newtons per metre).
A high k means the object is stiff and harder to stretch.
A low k means the object is easier to stretch or compress.
The amount of stretch or compression (x) – measured in metres (m).
The farther you stretch or compress an object, the more energy it stores.
The Formula for Elastic Potential Energy
If you double the extension x, the stored energy increases by four times.
Energy Transformations
When the stored elastic potential energy is released, it can be transformed into:
Kinetic energy – e.g., when a catapult fires a stone.
Gravitational potential energy – e.g., when a trampoline throws someone upwards.
Sound or heat energy – if some energy is lost in vibrations or friction.
Where is Elastic Potential Energy Maximum?
An object has the most elastic potential energy when it is stretched or compressed as far as possible without breaking or deforming permanently.
🎯 Top Tips
🎯 Think: stored energy – elastic potential energy exists before movement starts.
🎯 Not just metal springs – rubber, fabric, and many other materials can store it.
🎯 The more you stretch or compress, the more energy is stored – but remember it increases with the square of the extension.
🎯High k = stiff object – needs more force to stretch but stores more energy for the same stretch distance.
🎯 Units matter – energy is in Joules (J), extension is in metres (m), and spring constant is in newtons per metre (N/m).
🎯Elastic potential can turn into other types of energy – often kinetic or gravitational.