- #1

merper

I've heard that dp/dt can be written as f = m(dv/dt) + v(dm/dt)

Can someone tell me what this actually means, because it would seem that m would be dependent on v and v dependent on m, so im not sure how this would work out.

Also, can someone point tell me some important equations for springs other than f= -kx and e = .5kx^2