It is always the same as it was before the collision because there is no outside forces it is left with the same amount of energy throughout thee collision.
Scientists make hypothesis, or an educated guess. And they test there "guess" and see if there right or wrong. And they learn from there guess.
I hope this answer helped u
<span>Chemical reactions at the Earth’s surface </span>
Loud noise is particularly harmful to the inner ear (cochlea)
