Question

Hi there, I just wanted to ask why a collision is inelastic when kinetic energy is lost?

Answer 1

in an inelastic collision,the shape of the colliding bodies are deformed, the loss in kinetic energy of the system is due to the energy lost in the permanent deformation of the bodies.
for example,when two cars collide they are damaged.their speed is slowed down to a great extent indicating the loss in kinetic energy and the permanent deformation of cars i the main reason of this loss.

Answer 2

There's also the fact that energy likes to go into many forms, all the time! So there will be thermal energy, light, and sound! If you think of the car crash, bending metal makes it hot, sparks give off light, and you can hear the sound of a crash! These are all energies that come from the kinetic energy of the cars.

Answer 3

And so, due to the way energy likes to do that, you don't really ever have completely elastic collisions. You also don't find completely inelastic collisions. It's always somewhere in between. Lots of times, though, it's not too far from the truth to assume that a collision is purely elastic.