Hey guys. So I was doing this paper recently and I don't know how they got the answers for them 
for q 18, I don't really know how to do. But q19, my answer was D, because I thought the higher electrical resistance would mean induced eddy currents would lose a lot of their energy in the form of heat...can someone please explain why the answer is C?
Much appreciated!
(for some reason, it won't allow me to upload a screenshot from the two questions. It's questions 18 & 19 from the MC of 2012 physics!)
For 19, we know that
Now, position x is however far from the center of the earth (let's call it r), and position y is an extra half-distance (so 1.5r). Thus
Where M is the mass of the planet, and m is the mass of the thing.
^2}=\frac{GMm}{2.25r^2})
Putting Fx over Fy will 2.25, making the answer C.
As for 19, I had thought that you should have a high resistance as well. I thought that for my entire year 12 year; looks like I was wrong! I guess you just want to the electrons spinning as fast as possible, because if they're spinning faster they can consistently lose a lot of energy as heat. I guess that's just one to remember!
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