# Recent content by mr bob

1. ### Stability physics problem

Just ran through it trying splitting the triangle and i got OB = kmg(4a\cos\theta -4a\cos\frac{\theta}{2}) As this is equal to the GPE of the rod. mga\cos\theta = kmg(4a\cos\theta -4a\cos\frac{\theta}{2}) V = mga[(4k - 1)\cos\theta - 4k\cos\frac{\theta}{2}] Which is the correct...
2. ### Stability physics problem

Hmm. Since the triangle OAB is isosceles, could i split it into 2 right angled triangles to get the length of the extension in terms of \cos\frac{\theta}{2}? I'm not too clear why the sine of the angle theta can't just be used. Is there a fundamental flaw in my understanding of mathematics...
3. ### Stability physics problem

Just come across a question and I'm at a point where i see no further. A uniform rod AB, of mass m and length 2a, is free to rotate in a vertical plane, about the end A. A light elastic string of modulus kmg and natural length a, has one and attached to B and the other end to a fixed point O...
4. ### Simple Harmonic Motion

Thank you both so much! I finally got the answer.
5. ### Simple Harmonic Motion

How would i do this, impulse is applied. Would it be:-0 0.5 = 0.2v, where v is velocity?
6. ### Simple Harmonic Motion

A particle P of mass 0.2kg is attatched by an elastic spring of modulus 15N and natural length 1m to a point A of the smooth horizontal surface on which P rests. P recieves an impulse of magnitude 0.5Ns in the direction AP. Show that while the string is taught, the motion of P is simple harmonic...
7. ### Simple Harmonic Motion - Alevel M3

This is probably a really easy question. But alas the answer has eluded me thus far. Anyway, here is the question:- Points O, A and B lie in that order on a straight line. A particle P is moving on the line with S.H.M period of 4s, amplitude 0.5m and centre O. OA is 0.1m and OB is 0.3m. When...
8. ### Mechanics - Elastic springs and strings

Hmm, Ive cancelled it all down to get \frac{3mgl}{4} - \frac{2mgl}{3} + \frac{mgl}{3} = \frac{3mg(y - l)^2}{4l} - (Y - l)mg Which goes to:- 3(y - l)^2 - 4l(y- l) - \frac{20l^2}{12} Which after applying the quaratic formula, equates y - l = \frac{10l}{6}. (y - l) is the distance i...
9. ### Breakbeat techno metal thingy

Not too far off the reaction i was expecting:biggrin:
10. ### Breakbeat techno metal thingy

Hey guys, Have a listen to what i do when im not doing maths and physics (music wise). www.myspace.com/thevolatilegentlemen I hope you enjoy. It might make for some interesting late night (Britain) conversation. Or at the very least mildly annoy you.
11. ### Mechanics - Elastic springs and strings

EPE = \frac{3mg(\frac{2}{3}l)^2}{4l} The string is initially stretched by 2/3L as natural length is L and stretched length is 5/3L. I really appreciate your help Doc Al, this question has been giving me trouble for the last couple of days. Thank's once again.