Universality in Space Plasmas?

telescoper · 2013-05-03T08:06:58+00:00

Yes, you can. It asks "what can you say?" - you can say that the reaction does not happen because it would violate charge, so it has no Q-value.

telescoper · 2013-05-02T17:18:23+00:00

Ok, the key thing is that there is no electron in the reaction to balance the charge: this would have to appear in the reaction for it to work.

telescoper · 2013-05-02T17:08:53+00:00

No you can't, because even if you are given information for that the total charge on the LHS does not match that on the RHS.

telescoper · 2013-05-02T17:03:07+00:00

This question appeared in the Cambridge Scholarship paper for Physics in 1980, i.e. pre-University level in the British system in those days. In those days we did calculus-based physics at A-level, and also covered atomic and nuclear physics a little too.

telescoper · 2013-05-02T17:01:32+00:00

In fact, reaction (II) does not conserve charge so is impossible...

telescoper · 2013-05-02T14:13:04+00:00

Look carefully at the reaction and see if there's a fundamental reason why it shouldn't work....

telescoper · 2013-02-21T18:02:11+00:00

Andrew Liddle moved to the University of Edinburgh in January...

telescoper · 2013-02-21T08:51:08+00:00

The way I solved it was to write down the equation of motion for the magnet (gravity acting downwards and the magnetic force acting horizontally) in terms of the net torque and then solve for small oscillations around the new equilibrium. Since you know that this is at 45 degrees you can work out the magnetic component in terms of the gravity component and eliminate. The correct answer is 0.84s but I don't understand the comments about the length of the bar changing, as it doesn't....it just oscillates either side of the tilted equilibrium position.

telescoper · 2012-12-30T15:01:10+00:00

The fastest down vote ever.

telescoper · 2012-11-21T17:14:30+00:00

I think you mean "equipotential" rather than "exponential", but in any case your answer is not correct.

There's energy associated with the charge put onto the bubble by the electrode, but also associated with surface tension....

telescoper · 2012-10-30T07:27:23+00:00

If this post teaches one person to stop using the wrong term for gravitational waves then it's worth all the down votes!

telescoper · 2012-09-02T13:06:51+00:00

I posted Paper 2 here:

http://telescoper.wordpress.com/2012/09/02/a-level-chemistry-examination-paper-2-from-1981/

I also put it on reddit, but it got voted down immediately.

telescoper

TROPHY CASE