Recent content by barnaby

So if the contact is at the top, you get what is in effect two resistors in parallel - one at 24 ohms and the other at 6 ohms? I tried solving it like that... and got nowhere - calculated that the total resistance of the two strands of the circuit was 4.8 ohms... don't know if that's helpful at...

Homework Statement The circuit shown is used to produce a current-voltage graph for a 12V, 24W lamp: http://img338.imageshack.us/img338/9139/circuitlu6.jpg http://img338.imageshack.us/img338/9139/circuitlu6.jpg a) Calculate the resistance of the lamp in normal operation. b) Calculate the...

Well, both calculators are about the same price - the cost isn't that much of an issue. I'm just unsure which one to get - which one's the most powerful, the easiest to learn to use, the most versatile...

I'm about to buy a graphing calculator, and I don't know whether to get the Texas Instruments TI-84 (Silver Edition), or the Casio CFX9850GC+ (which has the added frivolity of a colour screen). I can't get the TI-89, because it has algebra software built in, and so I'm not allowed to use it...

Yep, that's exactly my trouble - I understand that Michelson-Morley disproved the 'aether', but I just don't really understand the physics behind what the truth is. It's conceptually difficult for me to visualise a magnetic 'field' - with a wave of, say, water, you can see what's carrying it -...

Can you suggest any books (other than the Feynman Lectures) which might help me do that?

You're right. I have no idea where to start with partial differential equations. As far as I know, ordinary differential equations don't crop up until FP1 of Further Mathematics, which I won't do till next year. \epsilon_0 - that's the 'permittivity of free space', right? Ah well, curiosity...

Come again?

P = \frac{F}{A}, where F is the force you are imparting, and A is the area over which you are imparting the force. If you increase the area, as you would by attaching plates of wood to your shoes, then the pressure under the wood will be less than it would be if you were simply standing...

Another thing that I've never really understood... As fas as I'm concerned, waves need a medium to travel through, but electromagnetic waves seem not to need one at all. I just can't visualise them as oscillations in anything. It sort of helps if I visualise EM waves as photons, because then...

That's what happens when you're taught science by someone who believes in Intelligent Design... :rolleyes: Thanks for the link.

I appreciate that that is true, but I can't really accept that as an explanation for *why* - as it just puts into an equation what I sort of already knew - I suppose the question I really want to ask is "what is gravity?"... ___ So \frac{GM_1 M_2}{d^2} gives the force with which one object's...

This is something that's been troubling me for a while: If I were to pull a 1kg mass with a force of 10N, it would accelerate at 10ms^-2. If I applied the same force to an object twice as massive, its acceleration would be half as large. However, everything accelerates at ~9.81ms^-2 under...

I started calculus in September (as part of A-Level Maths/Further Maths), and we've been told time after time not to look at derivatives as fractions. We recently did the Chain Rule, and we were told that a way to remember it was that if dy/dx = dy/du * du/dx, then the 'du's 'cancel out' -...

Oh, of course... the centre of gravity thing threw me a bit. Thanks!