# Recent content by John Park

1. ### Numerical Plot of Particle Orbits in Kerr Equatorial Plane

I don't know. But it occurs to me that conservation of energy might be a problem. The only cases of spiral orbits I can think of immediately involve some change of orbital energy--drag from viscous forces, emission of gravitational waves or absorption of electromagnetic energy as in a cyclotron.
2. ### Numerical Plot of Particle Orbits in Kerr Equatorial Plane

Not that's obvious to me. But it might be worth trying to narrow the range of possibilities first. Are you sure that spiral orbits are possible? Are there stable closed orbits in the Kerr metric? If so, it might be worth starting from one of those and trying to perturb it. ( Perhaps replace r...
3. ### Most efficient temperature to evaporate water?

It might help if you told us a bit more about your set-up. What sort of quantities of water, in what sort of vessels? (Other things being equal, water evaporates faster from a shallow open pool than from a deep tank.) What are your heat sources?
4. ### Numerical Plot of Particle Orbits in Kerr Equatorial Plane

Did you consider what relations between r and φ would give you a spiral and going from there?
5. ### Transmission for double delta-potential vs single delta

I suspect this is a strong hint. Is there a relation between the separation of the two deltas and the wavelength of the wave-function?
6. ### Rod falling faster than gravity

The weight of the rod has a component directed through the pivot and a tangential component causing acceleration.
7. ### Most efficient temperature to evaporate water?

The vapour-pressure of water increases much more than linearly with in creasing temperature. But vapour pressure isn't the only factor that determines the evaporation rate. In general air flowing over a water surface (or bubbled through water) will cause faster evaporation than still air (the...
8. ### Finding an indefinite integral

Try putting x=sinθ again and simplifying. Note that you seem to have made a sign error in your last integration.
9. ### Geometric average versus arithmatic average

Unweighted, the arithmetic mean is always >= geometric mean, so I suspect your weights may have to have a sum > 1. Think what happens if one of the numbers you're averaging is zero.
10. ### Occupancies in sub bands of a quantum well

I think it may be. Depends what "it" is, of course.
11. ### Why does (-1)^n(sin(pi/n)) converge when (sin(p/n)) diverges

How about this: For large n, sin(π/n) is approximately π/n, so the series is approximately πΣ(1/π) which is known to diverge. With alternating signs, the series approximates πΣ( (1/n) - 1/(n+1) ) which approaches π.ln(2). Actually I think I find it more persuasive to group pairs of successive...
12. ### Inertia tensor of a body rotating about 3 axes

It can't do that simultaneously, if that's what you're thinking. The body's angular momentum is represented by a vector--and that direction of that vector is the axis about which it rotates. The axis may not coincide with any of the coordinate axes, but it is a single axis.
13. ### I What does the magnetic moment of a particle depend on?

For elementary particles, the magnetic momentum depends on the angular momentum and the mass, though not necessarily in a simple way. For similar particles the magnetic moment increases with the angular momentum*. For particles of the same spin, the magnetic moment is roughly inversely...
14. ### I How to remove Ethanol from Gasoline?

Doing two separations with half a gallon of water in each should be more effective than a single separation with one gallon (and three separations would be more effective still). That principle would help you use less water.
15. ### I Light and the nature of space

I thought this was strictly for local measurements.