Velocity X Mass

[YT2095]

I`m sure this will seem a simple question to some of you (I hope) I`ts just that Ive forgoten how it works :(

a body weighing 1 Gram, how fast does it need to move to have the same effect as doudle it`s mass (2 grams)

example, I rest a 2 gram bullet on a peice of paper, it won`t go through it, I fire it, and it`ll go through steel plates, as if it mass was increased to several hundreds of pounds but with the same surface area (volume).

can anyone remind me of the formula/explaination again Please, it`s been Soooo long since I`ve had to use it! :)

[Cookie]

Well, to have the same momentum, you'd cut the velocity in half as you double the mass. For eg.

If you start with a 2g mass and it's moving 2m/s then the momentum is 4g m/s (yeah, I know the units should be in kg but you get the idea). If I change the mass to 4g, then my velocity would have to be 1m/s to get the same momentum.

Cookie

[Radical Edward]

that's just momentum. p=mv. the important thing is the strength of the resisting material. you can't really say it behaves like something with "twice it's mass" since that makes no sense, unless you want to play with relativity, in which case it will be a significant fraction of c.

[YT2095]

so lets see if I`ve got this right then, 2 grams at 1000 m/s would make the mass equiv for the same volume about,,, ok forget it LOL, my head`s not working right, and I got ppl calling me :(

[Radical Edward]

well the force applied by a mass of 2g is 0.02 N (roughly), however to figure this out from say, something slowing a bullet down, you need to work how rapidly the mass is slowed otherwise you are missing a per-second unit. (momentum is kg*m/s, force is kg*m/(s^2) )