In physics, the bounciness of a surface is called the “coefficient of restitution”. The coefficient of restitution is represented as a number between 0 and 1, which defines how much speed an object retains in the opposite direction along the line of impact after a collisionA collision occurs when the physics engine detects that the colliders of two GameObjects make contact or overlap, when at least one has a Rigidbody component and is in motion. More info
See in Glossary.
In PhysX, the Physic MaterialA physics asset for adjusting the friction and bouncing effects of colliding objects. More info
See in Glossary asset’s Bounce property has a value of 0–1, which represents the coefficient of restitution.
0 represents a completely inelastic collision (no bounce) 1 represents a perfectly elastic collision (full bounce) A value between 0 and 1 indicates a partially elastic collision with varying degrees of bounciness.
The default Bounce value in Unity is 0.
In physics simulation, you can also define a threshold at which colliders no longer bounce off each other. If two colliding objects have a relative velocity below the defined value, they do not bounce off each other. To configure the bounce threshold, go to the Physics Settings (Edit > Project Settings > Physics) and set the Bounce Threshold to the minimum velocity at which colliders should bounce. This value is set to 2 by default.