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Overview
An elastic collision is a collision where total momentum and total kinetic energy are conserved. It is an ideal model that shows how objects can exchange motion without permanent loss of mechanical energy.
Momentum Conservation
Momentum is conserved in an elastic collision if the system is isolated. Direction must be included because momentum is a vector.
Kinetic Energy Conservation
What distinguishes an elastic collision is conservation of total kinetic energy. Individual objects may gain or lose kinetic energy, but the total remains the same.
Ideal Model
The elastic model assumes energy is not permanently transformed into heat, sound, deformation, or internal energy.
One-Dimensional Elastic Collisions
In one-dimensional elastic collisions, conservation of momentum and kinetic energy can be used together to solve for unknown velocities.
Energy Transfer
Kinetic energy can transfer between objects while the total remains constant.
Real-World Limits
Most everyday collisions are not perfectly elastic. Some energy usually becomes heat, sound, vibration, or deformation.
Common Mistakes
A common mistake is assuming every bounce is perfectly elastic. Another is conserving kinetic energy in a collision that is actually inelastic.
Applications
Elastic collision models are used in kinetic theory, molecular motion, particle physics, billiards, and air-track experiments.
Why This Matters in Physics
Elastic collisions demonstrate the combined power of momentum and energy conservation.