Recent content by aloyisus

Thanks for looking over it, Naty1. I'm glad it makes sense. I'll restate my question about the Lagrangian. In order for the laws of physics must be the same in all inertial reference frames, Lagrange's equations of motion must keep the same form in all inertial reference frames, which...

I'm working my way (slowly) through Landau & Lif***z Classical Mechanics. I'm finally nearing the end of chapter one, and although I hit another stumbling block, I think I've got it now. If anyone has the time to check my reasoning, I'd be grateful. I will quote the passage that was confusing...

OK, I think I've finally got it. If anyone's still listening, does my reasoning below make sense? We have \frac{\mathrm{d} }{\mathrm{d} t} (\frac{\partial \L}{\partial \mathbf{v}}) = 0 which means 2v_{i} \frac{\mathrm{d} \L}{\mathrm{d} v^{2}} = constant for each of the three components. Now...

Thanks stevenb, I'm going to go away and think about what you just said ;)

kcdodd, thanks for the link. That's a good companion to the first chapter of Landau, but he doesn't provide any more information at the place where I'm stuck. If we ignore my counter-example, and I try to state my problem really simply, we have a function \L which is a function of v^{2} only...

Thanks for your reply, kcdodd. Any stab is appreciated. Landau doesn't introduce Hamiltonian formation until much later in the book, so I'm not sure that's where he was going. His statement "since \frac{\partial \L(v^{2}) }{\partial \mathbf{v}} is a function of the velocity only, it...

I'm coming back to physics after a long absence of fifteen years. Starting with classical mechanics, I thought I'd read Landau & Lifgarbagez, since I already have it. I know it's famously concise, but I didn't think I'd be stuck on page 5. If anyone can help me unravel the following, I'll be...