Recent content by Jack111

I should restate the queston. You have two bodies, of equal heat capacity, with temperatures T1 and T2. You run a reversable heat engine between them. How much work do you extract and what is the final temperature? You can calculate it by saying entropy is converved, so C ln T1 + C ln T2 = 2C...

Are you trying to integrate the expectation of the coulombic interaction operator over two wavefunctions? <a(r1)|J|b(r2)> ? (with r1, r2 position vectors so in general dependent on r, theta and phi). If so, which wavefunctions a and b are you using? You'd also need to rexpress the 1/r term in J...

Very difficult to calculate without some microscopic details of the system. If you had a hysteresis curve for the material you could calculate the field strength nearby the magnet roughly, but it'd still be geometry dependent and probably not that accuracte to the real system.

The work done AGAINST GRAVITY will be the same. You will need to do work on the spring to extend it to the point that it exerts a 50N force on the weight, after which point you will lift the weight normally. The work that you've done on the spring is recoverable later since it's stored as...

F? BTU? cubic feet? Sounds like Newton's law of cooling here but you're going to need to flesh it out a bit and convert all units to SI first

As the demonstration on that berkely website shows, in the static case metals shield electric fields from their interior. Anyone familiar with gauss's theorem in electrostatics might like to consider a gaussian surface throughout the interior of the hollow conductor enclosing the cavity to see...

In fact, if it's reversable, then the entropy increase of the surroundings exactly matches the entropy decrease of the system.

Even in the static case it's not that simple. In our astrophysics course last year we were told that in fact it's very hard to find stable configurations in the attractive N-body case. The only link I can find off hand is http://www.astro.uni-bonn.de/~pavel/movie.html which shows a simulation -...

Hi all, Sat this problem in an exam recently and it's got me wondering. First off, you have a reservoir at a lower temperature T1. You also have a mass of water at a higher temperature T2 (in this case it was 10C and 100C, I can't remember the mass but let's say it was 1, and Cv 4.2). First we...