Recent content by mLuby

Good point Integral, but to make this easy I'm just interested in the heat a capacitor can generate via short circuit. I'm now investigating lead, nichrome and copper as potential heating elements. So far lead seems to be the best in terms of requiring the lowest voltage. Any suggestions on...

Hmm, maybe nichrome isn't the right material, or 1mm isn't the best thickness. Yes, I am ignoring cooling for now. The application is a steering wheel heater, so it needs to go from 0°F to 60°F very quickly (≤6s) but then the hands will keep it at temperature. The wire will be split between two...

Thanks Baluncore, I'd totally missed that. Recalculating: • Wire resistance: 3.6 Ω = resistivity * wire length * cross section area of 1m^3 / wire cross section area • Current needed for Joule heating: 8.0 A = √(heat needed / wire resistance • Time to discharge 2/3 energy: 180 s = resistance *...

Hi PF! I'm working on a portable heating circuit. I'd like to use an ultracapacitor charged by 2 AA batteries to increase the temperature of 2.25m of 1mm Nichrome wire by 34° in 6 seconds. The question is, what capacitance does the ultracapacitor have to have? Initial values: •...

I figured it would be basic because flows over infinite flat planes and perpendicular to infinite cylinders are often covered in the introductory texts I've read. Obviously that assumption was incorrect. My understanding is that at hypersonic speeds most of the form drag & kinetic energy lost...

Hi Physics Forums! I would like to know how to model a thin, infinitely-long circular cylinder moving axially at hypersonic speeds. For something I would expect to be a base case in most hypersonics textbooks, it's surprisingly difficult to find a straight answer. In particular what is...

Wouldn't your array attract the charged particles as often as repel them, with no net effect?

This sounds similar to supercavitation, though with a plasma bubble in air instead of an air bubble in water. Wonder how you'd supercavitate in a solid–with a liquid bubble?! http://en.wikipedia.org/wiki/Supercavitation