[Physics] How to tell if the collision is elastic or inelastic

collisionconservation-lawsenergy-conservationkinematicsmomentum

I'm a programmer and a game developer, not a mathematician or a physicist. So please go easy on the math 🙂

I know two things:

However what I need to know is: given the mass, the velocity, and the 'angle' the two objects are going two be when they collide – how can I know if I need to compute an elastic or an inelastic collision?

I need this for the 2D game I'm developing, that tries to simulate relatively-realistic physics. Thanks for your help

Best Answer

If the total kinetic energy before the collision equals the total kinetic energy after the collision, the collision is elastic. Otherwise, it isn't elastic.

given the mass, the velocity, and the 'angle' the two objects are going two be when they collide - how can I know if I need to compute an elastic or an inelastic collision?

The mass, velocity and angle do not give you any information on the type of collision.

It is the nature of the objects themselves that determine the nature of the collision.

Compare two different collisions where mass, velocity and angle parameters are the same. One is a collision of two ball bearings balls (hard, round, smooth) and the other a collision of two balls of clay (soft and somewhat lumpy).

The collision of ball bearings will be effectively elastic (with negligible losses). The clay balls will not rebound smoothly and may even stick together, perhaps coming to a near stop. Since the kinetic energy is drastically reduced, the collision is inelastic.

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