Am I getting anything wrong here?
I think a knife uses force over a small area rather than energy, as pressure to cause cuts, splits and cracks.
A club can have the same pressure as the knife, but the club carries greater momentum and will knock around things more.
A bullet causes damage through the energy it carries and causes heat and deformations as it hits the target.
When people talk damage with bullets they use energy, but with melee it’s usually force. But when should I use them? Both are used at the same time but one is doing more of the effect. Don’t both result in work?
Like a force over a distance is work and thus the same as kinetic energy. Joules.
But if it’s pressure doing work I get unsure. I mix up how things break all the time.
In: Physics
I am not really sure what your question is, and you also threw around a lot of terms that are completely different from each other. It is also important to note that the way we use physics terms in our day to day lives are not at all representative of the true definition of these terms. Anyway here is the briefest physics course you will ever receive.
**Momentum** is how hard it is to stop something. It is equal to speed times mass.
**Force** is equal to the change in momentum over time. Basically how quickly something would be gaining momentum if it were allowed to move indefinitely.
**Work** is a form of **Energy**. There are many forms of energy, but the energy you are referring to is the work done on an object, i.e. a **force** applied over some distance. ex. you do more work when pushing a box 3 feet than you do when you push it 5 feet, even if it takes the same amount of force to move.
**Pressure** is the concentration of force per area. Ever heard of PSI like for air pressure or when blowing up a ball? That is **P**ounds of force per **S**quare **I**nch of area.
Additionally, the energy of a bullet isn’t *directly* related to the damage it can cause. You can tell very little about the damage something can do from it’s kinetic (movement) energy alone. There are SO many things to consider here. You have to consider the size and shape of the object. You have to consider the angle and distance which the object is traveling, and most importantly you have to consider **the way the energy is transferred from the object, and how it dissipated in the target.** If I shot a big ball of jello, it wouldn’t do much damage as Jello is highly viscous and nonrigid, causing it to dissipate the energy quite well. If I shot a ceramic plate, it wouldn’t fare so well as ceramic is fragile and rigid, and prone to weak areas in the construction.
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