Recent content by laddhoffman

The tangential acceleration is also nonzero, because the tangential velocity, though constant in magnitude, is changing direction. Oh, wait, I see what you mean. Yes the Earth is not increasing or decreasing its rotation speed appreciably!. Though, if we want to take a larger view - i.e. we are...

Sounds to me basically a case of impulse. Bottle collides with tree; fluid inside rebounds more than glass does, since it is more elastic; rebounding fluid collides with cork, pushing it out. The collision with the tree is not very inelastic, and that kinetic energy has to go somewhere: the cork...

Well I think you're in good shape as far as the original proof is concerned. It is possible the problem specifies scleromic so that static equilibria can in fact exist, and that the problem inherently does not apply to a rheonomous system. Extending the consideration to rheonomous systems...

Ok, I've worked through your proof. The only point, and it's a minor one, I would bring up with the mathematics, is that I'm not sure you need \nabla_i. I think you just want \delta q_j = \sum_i \nabla q_j\cdot\delta \vec{r}_i. But, this doesn't seem to significantly alter the proof...

I noticed this question and bookmarked it to see if anyone would take it up. Since no one has, I will take a stab myself. I'm out of practice so don't know how much help I'll be but maybe I can at least stimulate some discussion. One question I have is, why do you introduce F_i and r_i, and...