<p>I don't know about the tubes either.</p>
<p>The +2q one I got. The top right one would move southeast because it is pulled right by one +2q and down by another. the bottom right charge has much less force on the top right one.</p>
<p>Does anyone know about the liquid that is at the brim, cooled and goes down, then heats up back to the brim?</p>
<p>The eV I wasn't sure about.</p>
<p>I was thinking it could have been III (v constant) but I don't know now.</p>
<p>Yes, that was the electrostatics one I was talking about. I think I chose northeast. </p>
<p>Momentum was 1/3 (the one with the disk)</p>
<p>Oh, what was the one with the coil and the magnet and the second coil (to induce current, ac, dc, or constantly increasing). Was it all three?</p>
<p>For the brim, I think the coefficient of expansion (or however they phrased it) was larger for the bucket than the water (the last answer).</p>
<p>For the tubes - was the second question answered by wavelength? The first question was what was a possible wavelength (5, 10, 15, 20, and 25). The second was which one changes when the tube expands (I believe).</p>
<p>From what I remember, I kept interpreting the tube problem backwards from how it was drawn.</p>
<p>For the other problem: magnetic force between two parallel charge = 0?</p>
<p>Hmm, possible, was it Newton or Galileo who first came up with the idea of reference frames?</p>
<p>For the sound waves, path difference for constructive interference is m<em>lamda while path difference for destructive is (m+1/2)</em>lamda. I think the answer was 20 for that one.</p>
<p>I almost worked out the tube one, I knew it had something to do with the path length difference and since it was exactly destructive interference the waves were separated by half a wavelength or something but I didn't have time to finish</p>
<p>let's see...
the person on the merry-go-round was 240 N (requires 4 times the force)</p>
<p>what about the one that was like which is not an example of electromagnetic radiation
a) ??
b) discharging a capacitor
c) moment after you connect wire to battery
d) electron moving at constant velocity
e) electron accelerating</p>
<p>electron moving at constant velocity does not produce an em wave</p>
<p>two currents moving in the same direction attract each other. one creates a magnetic field that affects the other one</p>
<p>A was an antenna with an alternating current</p>
<p>I think it is B.</p>
<p>Hmm....isn't it E=vBl*sin(theta) for a magnetic field?</p>
<p>sn3- oh, now I feel stupid. it was the coeff of expansion.</p>
<p>I put 5 I think for the first tube question. A guess.</p>
<p>Why do you multiply by 4 for the merry-go-round?</p>
<p>For merry go round, all I knew was:</p>
<p>V=2(pi)r/T and a=v^2/r, so it had to be times four
(or something like that)</p>
<p>74 was d=mg/k
because
F=ma
F=kx
ma=kx
x=ma/k</p>
<p>Right?</p>
<p>Last one was
sqrt(xA^2/m) ?</p>
<p>I second d=mg/k.</p>
<p>Does anyone know about the one with the positive leaves, with a rod pulling them apart more? it was north or south end, right? I put negative.</p>
<p>Bottom were positive, top was negative, bar was negative.</p>
<p>Were there any flux questions?</p>
<p>voltage = blv is for a conductor moving in a magnetic field</p>
<p>for the two wires, do you know the two right hand rules?</p>
<p>magnetic field set up by one wire is B = uo<em>I/(2</em>pi*r)</p>
<p>Force due to B on the other wire is then Fm = B<em>i</em>l*sin(theta)</p>
<p>direction is according to the right hand rules</p>
<p>Fc = m<em>w^2</em>r
where w=2<em>pi</em>f</p>
<p>double the frequency, centripetal force is quadrupled</p>
<p>last one is just conservation of energy
1/2<em>m</em>v^2 = 1/2<em>k</em>A^2</p>
<p>I forgot what quantity they asked for though</p>
<p>no there werent
man those modern physic questions suck big time when common sense doesnt work..</p>
<p>I know the right hand rule, but I thought the magnetic force between the two currents was zero for some reason.</p>
<p>For the one with the stream of photoelectrons (I think), was the answer frequency?</p>
<p>What about that funky one with the two masses and (x and y) where the gravitational potential energy was least for y; was it the point all the way to the left?</p>