Recent content by dorker

Help me clear up something. I know the magnetic field of an electromagnet's core is given by , where N is the number of turns of wire. Now, the resistance of the wire is given by R = ρ*λ/A, where ρ is the resistivity, and λ the length of the wire. Using Ohm's law to combine them, I get: But...

I hear a setup like the one in the pic will drain the battery in minutes, and using an AC source will mean an oscillating field and heating. So what other options do I have for a power source if I want a working homemade electromagnet?

Eddy currents and heat losses? Is there anything else?

I want to make an electromagnet to rapidly switch polarity back and forth. I hear the core should be made of laminated iron to avoid heat losses; is this correct? Where could I get one such core from, and is there anything else I should consider?

Sorry to keep pestering you, but which ones? I'd simply assume it depends on the bodies not getting deformed, but you just said it didn't depend on hardness.

So, I'm not sure I get this. Is there any way to know beforehand whether a collision will be elastic? Does it depend on the freedom of movement the bodies will have?

^ Ok, thanks for the answers.

So to be clear, can collisions between sufficiently "hard" bodies be assumed as nearly elastic, regardless of shape?

The wikipedia article on collisions says "collisions between hard spheres may be nearly elastic". It doesn't elaborate nor give a source on the statement. I was wondering about those two conditions. Hardness I understand, but is the spherical shape necessary? Is it about there being a single...

I distinctly remember the audience dying in laughter at Sheldon saying his Nintendo 64 arrived, and other such "jokes".

I see. Thanks.

Someone told me I'd be more likely to get help here. Say you have these two balls moving in opposite directions. The balls float in the air and thus by themselves have negligible friction, but each is carrying a (detachable) bar across the ground, which has friction. On the very instant the...

^ You sure about that? An elastic collision is one where there's no kinetic energy lost. And friction is the main thing one would think it's lost to. About your example, a car can't be properly modeled as a single body. A lot of energy is probably lost between the different pieces that compose...

Say you have these two balls moving in opposite directions. The balls float in the air and thus by themselves have negligible friction, but each is carrying a (detachable) bar across the ground, which has friction. On the very instant the balls collide with each other, they let go of their...

This. Seems to me like all the "jokes" consist of is "WE'RE REFERENCING NERD STUFF, NOW LAUGH!" References by themselves do not make comedy.