Energy is defined in physics as the capacity to do work, which is the movement of an object against a force. This capacity is present in many different forms throughout the physical world. Energy is categorized broadly into two primary types: kinetic energy (the energy of motion) and potential energy (stored energy). Potential energy is the energy an object possesses due to its position or internal configuration, ready to be converted into other forms when released.
The Definition of Stored Elastic Energy
Elastic energy is a specific form of mechanical potential energy stored within a physical system when a force is applied to deform it. This energy is accumulated when an elastic object is temporarily stretched, compressed, twisted, or bent from its natural, resting shape. The work required to deform the object is converted into this stored elastic energy, which remains stored only as long as the object is held in its deformed state.
The potential nature of this energy comes from the object’s inherent tendency to return to its original configuration. This tendency is driven by an internal restorative force that acts to oppose the deformation. When the external force is removed, the stored elastic energy is released, and the restorative force converts it into kinetic energy as the object snaps back to its equilibrium position.
Where Elastic Energy Is Found
Elastic energy is used in many common devices designed to store and release energy. A classic example is the mechanism in a wind-up clock or toy, where a coiled spring is tightened to store energy that is slowly released to power the movement. Vehicle suspension systems utilize heavy-duty springs to absorb the energy of impacts, temporarily compressing the spring and then releasing the energy to restore the car’s position.
In sports, the elastic properties of materials are deliberately manipulated to maximize performance. A drawn bow stores substantial elastic energy as the string is pulled back, bending the limbs. Releasing the string allows this stored energy to be transferred rapidly to the arrow, propelling it forward. Similarly, a diving board or a trampoline stores elastic energy when a person lands on it, which is then released to launch the person upward.
The Underlying Principles of Elasticity
The storage and release of elastic energy are governed by the material’s physical properties, specifically its ability to withstand deformation. When a deforming force is applied, the material’s internal restorative force acts in the opposite direction to resist the change. For many materials, the strength of this restorative force is directly proportional to how far the object is displaced from its resting position.
This proportional relationship holds true only up to the elastic limit. The elastic limit represents the maximum stress a material can endure without undergoing permanent deformation. If the object is deformed beyond this limit, the material structure changes permanently, entering a region of plastic deformation where the work done is no longer stored as recoverable elastic potential energy.
The physical mechanism for this behavior is rooted at the atomic level, where atoms behave much like they are connected by tiny, stiff springs. When an external force is applied, these interatomic bonds are stretched or compressed, temporarily storing potential energy. The stiffness of these atomic “springs” dictates a material’s elastic properties, determining the maximum energy that can be stored before the elastic limit is reached.