Quick question about elastic/inelastic collisions

[bestinthewest]

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Correct me if I'm wrong, but I have ingrained in my head that elastic collisions employ conservation of energy while inelastic collisions utilize conservation of momentum. Conversely, elastic collisions also display conservation of momentum, but in inelastic collisions there is no conservation of energy. This last part is evident in the the example where a stationary ball collides with and sticks to a second ball. The kinetic energy of just the first ball is lost when it collides and sticks to a second ball since the pair will travel slower than just the first ball before it made contact. Is this thought process correct? Thank you.

 

[bestinthewest]

Yes. That is correct.

Elastic Collisions: momentum and energy conserved
Inelastic Collisions: momentum conserved, energy not conserved
Perfectly Inelastic collisions: momentum conserved, energy not conserved, objects stick together after collision

For inelsatic collisions, energy may be lost to heat as the objects do not perfectly bounce off of one another, but rather deform after the collision or remain stuck together. Hope it helps.

Moreover, elastic collisions display no deformity and will thus bounce off. As an example, clay balls colliding would exhibit an inelastic collision, whereas rubber balls would bounce off one another and are therefore elastic. Wonderful, thank you.

 

[azor ahai]

If you want a real world example to gain intuition about elastic collisions, think of pool balls or a Newton's cradle (those things you see on people's desks in tv shows). Though these aren't "perfectly" elastic, because some energy is lost as sound.

Another example are ideal gas particles. What's important about this? The pressure in a tank of ideal gases is not caused by transfer of energy, but by change in momentum of that gas particle that hits the wall. This is an impulse and think of impulse as the force (with a certain duration) that causes the pressure (force over certain area) on the wall of the tank.

Reconceptualize Newton's laws in terms of momentum-impulse and you'll be golden.