Bouncing

Bouncing is the rapid contact and rebound of an object with a surface after impact, driven by elasticity. It is common in sports and toys, such as a basketball rebounding after ground contact, but also occurs in liquids, granular media, and biological systems. The rebound results from temporary deformation that stores energy and later releases it as kinetic energy.

In physics, the collision is characterized by the coefficient of restitution, e, which equals the ratio of rebound speed to impact speed along the normal. For a perfectly elastic collision, e = 1; in real systems e < 1 due to energy losses from internal damping, heat, sound, and surface deformation. The bounce height is related to e; after each drop, the maximum height multiplies roughly by e^2 in simple models.

Several factors influence bounce: material elasticity, stiffness, and damping; surface hardness and texture; shape and mass of the bouncing object; impact velocity; temperature and air resistance. Softer, more damped materials yield lower e and lower bounce heights; harder, more elastic materials produce higher e and higher rebounds.

Applications include sports equipment design (balls optimized for specific rebounds), trampolines and playground surfaces, shock absorbers and safety flooring, and material testing. Bouncing is also used to study material properties and energy transfer, and appears in natural phenomena such as raindrops contacting surfaces and seeds or droplets that rebound under certain conditions.