Bullets and Truth: Exploring Momentum and Energy

[phil]

Good afternoon -please bear with me -I had to skip physics as a subject -so my knowledge is good in some places, non-existant in others.
There was an interesting post in the archives about the momentum of a bullet -that if two bullets impact with the same energy, the one with more momentum will "kick" more?
Momentum is virtually never mentioned in the gun press, but Energy (KE) is a lot -but what does it actually mean? If I shoot something the momentum is what moves the object back -what difference would different levels of energy have? If two bullets have the same momentum, the lighter one will be faster, so have greater KE -what practical effect does that produce?
Related question -a hollowpoint bullet will mushroom when it strikes a liquid/semi-liquid due to a hydraulic effect if the bullet is moving fast enough -is this governed by KE or momentum -is the hollowpoint more likely to open if I make the bullet heavier or make it lighter and faster?
phil

 

[Arcon]

Originally posted by phil
Good afternoon -please bear with me -I had to skip physics as a subject -so my knowledge is good in some places, non-existant in others.
There was an interesting post in the archives about the momentum of a bullet -that if two bullets impact with the same energy, the one with more momentum will "kick" more?
Momentum is virtually never mentioned in the gun press, but Energy (KE) is a lot -but what does it actually mean?

The kick is related to changes in momentum. However you can't be too careful when considering such statements.

Kick is a force. Force is change in momentum per unit time. The same change in momentum will give a different forces when the time during which the change occurs differs.

The rest of your questions concern damage and that's pretty complicated. Basically, all other things equal, more kinetic energy - more damage. But not all things are usually equal

 

[phil]

Thanks for the reply
"more energy, more damage"
Main damaging mechanisms of a bullet are the depth and width of the wound channel (there is energy being lost to the stretch cavity -but that produces little damage with handgun rounds) -how does more KE contribute to these? Does more KE mean deeper penetration?
Any ideas on what the forces that mushroom the bullet are?
phil