No! to Backyard Fireworks

[BrianR]

Originally Posted by footfootfoot

I think you snoozed through physics class, Brian. If you shoot a bullet straight up in the air, it loses its energy at the apogee of its arc. When it reaches the ground it is going just as fast as when it left the barrel. A flat trajectory, not so.

Incorrect, although the bullet will regain some momentum, it will not regain it all. Yes, there is a moment a the top of the arc when the bullet is motionless, and there is an acceleration curve on the way down, the final velocity is nowhere near the initial velocity. Had I not snoozed through physics, I could even offer equations to prove this. Someone else will have to do it for me.