<p>Am I the only one more nervous about Mechanics than E&M?
I seem to be able to do E&M FRQs pretty well but not Mechanics. x_x</p>
<p>^ I agree! I am so nervous about the physics c mechanics tomorrow. I suck at frq with a capital S! Anybody have any ideas on possible frq tomorrow?</p>
<p>Also, can anybody explain the basic idea behind torque? I do not get torque at all. 
which is pretty bad considering the test is tomorrow! anybody pulling an all-nighter?</p>
<p>I sure hope there is minimum momentum/collision problems. Rotation may be killer as well.</p>
<p>yeah, momentum and collision is pretty easy. i hate gravity questions and torque! what are kepler’s laws?</p>
<p>You’d think momentum/collisions are easy, but they had a killer one in a recent test…it was within 5 years…2004-2005 or something. Hope ours is fairly straightforward (if we get one).</p>
<p>For torque, the best thing to do is pick an axis of rotation where the most perpendicular forces are acting. Then use sum of forces = ma [since this is rotation, we do sum of torques = I(alpha)]. It might get a bit confusing with which ones to subtract and which ones to add, add the ones that help the direction of rotation and subtract the torques that oppose the direction of rotation.
Yea, that should work. Lol I haven’t done torque problems in a long while.</p>
<p>thanks! 
i really hope our frq are straight forward…another thing, how do you find the coefficient of friction? i know that is pretty easy but i feel like i dont remember anything!</p>
<p>The main thing you need to know for that is
Force of friction = (coefficient of friction) x (normal force).</p>
<p>If there’s an applied force, something will equal the Fn…then the y-components will cancel out and stuff. You can figure it out if you work through it. Oh, and make sure you use it right (as in if its static or kinetic friction).
If the object is rotating aswell, it gets even more crazy. -_-</p>
<p>Btw, anyone know if buoyancy is on the test or not?!!</p>
<p>^ no buoyancy is not on the test…thank goodness :D</p>
<p>i am really nervous for this test tomorrow!</p>
<p>My prediction for the E&M FRQs:
- Gauss’s Law + potential at specified points (might be some crazy shape instead of a sphere/cylinder; haven’t seen one for a weird shape in recent years)
- Circuit analysis (complex circuit build-up, double switches…diff.eqs for stuff).
- Jumbled-up mix of an object moving in electric+magnetic field, find induced I, direction of induced current flow and all…</p>
<p>I’d actually do well if it was like this.
Mechanics, however…</p>
<p>For mechanics, I’d like a box-spring system, projectile motion, and static equilibrium. Oh, and a side of fries and a milkshake with that.</p>
<p>^ I’d love that too.
If I see: Collision, Rotation+Energy and F=ma,
it’ll be my happiest AP ever (yes, happiest, not easiest).</p>
<p>Hey guys, when they ask for maximum velocity, in general, what should I look for first ??</p>
<p>Yay circuits.</p>
<pre><code>S R1
</code></pre>
<p><strong>/ </strong><em>///_</em>____________
| | |
| | |
__ __ /
- V C __ \ R2
| | /
| |
| | |</p>
<h2>| | |</h2>
<p>Find the current supplied by the battery as a function of time.</p>
<p>^Huh? I won’t even pretend to know how to decipher that.</p>
<p>I see a switch and a Resistor R1, but other than that it seems easier if you explain it lol. Yeah I can’t even tell where the battery is supposed to be lol.</p>
<p>for the E&M I would love to see Gauss’s Law, Circuitry, and Induced voltage. That would be what I want to see. For Mechanics It’s all good as long as they take it easy on the rotation. I still try to find the moment on inertia using the double integral of rho r^2 dA.</p>
<p>We aren’t supposed to have AC circuits on here are we?</p>
<p>Omg that picture was fail… I had it spaced out nicely in the post but apparently CC decides it doesn’t like my spacing… lol</p>
<p>Anyway, you have a battery with a voltage V with a resistor R1 on the high potential side of the battery. You then have a capacitor C and a resistor R2 connected in parallel to that. Find the current as a function of time after the switch is closed.</p>
<p>Yeah, I’m hoping for something similar. For E&M, I would also like to see Gauss’ law. I hope they just have some random gaussian surfaces, either spherical or cylindrical (because that’s all I really know how to do). There will probably be a circuit problem with a capacitor, which generally aren’t too bad. There will also probably be a magnetic problem. I hope it’s a two part thing: 1)a charge moves in a magnetic field, find all these mechanics related things and then 2)a wire is in a magnetic field, find the induced EMF (one is a straight wire in constant magnetic field, the other will be a loop).</p>
<p>@RamblinMan: You don’t need to know how to do double integrals for Physics C, lol. I’d kill myself if we had to solve them.</p>
<p>Yeah, I’m also hoping high for a Gauss’s Law + potential, Circuit and Magnetic field (induced EMF on the moving object and all)…
I hope they don’t go crazy on us this year and ask something overworldly (like Biot-Savart on a crazy shape that we’ve never seen before; I’d collapse in the testing toom).</p>
<p>@feuxfollets: Lol is there switch/double switch somewhere? Or just the circuit?</p>
<p>No just a single switch. </p>
<p><strong>S</strong>*** R1
<strong>/ </strong><em>///_</em>____________
| <strong><em>|</em></strong> |
| <strong><em>|</em></strong> |
_<em>*** _</em> *****<strong><em>/
- V </em></strong><strong><em>C __</em></strong>***** \ R2
| *****<strong><em>|</em></strong> /
| *********<strong><em>| *</em></strong><strong><em>
| </em></strong><strong><em>|</em></strong>*** |</p>
<h2>| *****<strong><em>|</em></strong> |</h2>
<p>Hmmm there you go, just ignore the *'s</p>