ScienceGrade 2nd· Why Do Bouncy Balls Bounce?

Why Do Bouncy Balls Bounce?

Words to Know

Elasticity: How well something can squish and then spring back to its shape; Rubber has high elasticity — it squishes and bounces back!
Squish: When something gets pressed flat for a moment; A bouncy ball squishes when it hits the ground.
Spring back: When something returns to its original shape after being squished; The ball springs back and pushes itself up into the air.
Coefficient of restitution: A number that tells you how bouncy something is; A rubber ball has a high coefficient of restitution because it bounces well.

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What does “Elasticity” mean?

A bouncy ball bounces because of elasticity — the ability of a material to deform (squish) under pressure and then return to its original shape.
Source: American Physical Society
When a ball hits the ground, it compresses, storing energy. When it returns to its shape, that stored energy is released, propelling the ball upward.
Source: NASA
A Super Ball (made of Zectron, a type of synthetic rubber) can rebound to about 90% of its drop height.
Source: Popular Mechanics
Hard materials like glass or metal do not deform easily, so they don't store and release energy the same way — they either crack or barely bounce.
Source: Physics Classroom
The coefficient of restitution (ratio of bounce height to drop height) measures how bouncy a material is. Rubber has a high coefficient; glass and metal have very low ones.
Source: American Journal of Physics
A bowling ball barely bounces because it is too heavy and rigid to deform significantly on impact.
Source: Physics Education journal

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