4. Why does time play an important role in collisions? a) Time plays no important role in collisions
b) The longer the time of the collision, the smaller the force
c) The longer the time of the collision, the larger the force
d) The shorter the time of the collision, the smaller the force

The longer the time of the collision, the smaller the force. (B)

That's why, if you fall off the roof, you want to be stopped by a net or a pile of leaves, and not by the ground. You want the stop to last as long as possible. Like everybody says:  It's not the fall that hurts, it's the stop at the end.

vapour or gas assuming atmospheriv pressure

grav potential energy