Can someone explain elastic vs inelastic collision?

We've all seen the definition everywhere. Elastic collision is when kinetic energy is conserved and inelastic is when kinetic energy is not conserved. But what does this really mean? I have done the lab in physics class with the two pucks on the air table. The first test was colliding the two pucks on... show more We've all seen the definition everywhere. Elastic collision is when kinetic energy is conserved and inelastic is when kinetic energy is not conserved. But what does this really mean?

I have done the lab in physics class with the two pucks on the air table. The first test was colliding the two pucks on different angles (elastic) and the other test was colliding the two pucks but with the addition of a velcro so they stick and become one (inelastic).

What is the 2nd test inelastic? How is kinetic energy lost compared to the first test? If someone could explain this I'd greatly appreciate it as I would learn alot.
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