<p>Remember, you can derive any and all gas laws out of PV = nRT. If volume and moles are held constant, but pressure and temperature change, you just write two equations and solve for P and T. So P/T = nR/V, and Pi/Ti = Pf/Tf.</p>
<p>K = 1.5kT = .5mv^2, where k = Boltzmann’s constant and v = rms velocity</p>
<p>Test #2 MC, question 45.</p>
<p>According to them, the answer is A. I thought change in potential energy equals charge times voltage, not charge times voltage times distance.</p>
<p>Also, for question 47. I’ve done the right-hand rule it and looks like loop B would have to produce flux into the page to its right to oppose the decreasing flux into the page from loop A to its left. So the loop would have to be counter-clockwise as well. Is there something I’m doing wrong?</p>
<p>remeber total internal reflection is only one sided, it can only happen on the side that has the greater index of refraction.</p>
<p>Israel, what test are you referring to?</p>
<p>Princeton Review.</p>
<p>Ah alright. I don’t have it, but EPE shouldn’t be equal to qVd. EPE = qV, and V = Ed, where E is field.</p>
<p>For gravity we use g=-10m/s2 right?</p>
<p>That is correct. I think it’s acceptable for the FRQs, and it’s pretty much required for the multiple choice since you can’t use a calculator.</p>
<p>More random review! Don’t confuse your electric laws.</p>
<p>F = kq1q2/r^2
U = kq1q2/r
V = kq/r</p>
<p>do we have to know Resolution for the ap exam?
or diffraction gratings?</p>
<p>I know we have to know diffraction and if by resolution, you mean magnification, then yes.</p>
<p>Someone help me on the Lenz’ law thing.</p>
<p>^ yeah the PR q. 45, confused me as well…I was absolutley positive that it was qV and not qVD, however, in the question that follows, they once again incorporated d when they shouldn’t have…</p>
<p>Lenz’s law simply states that current (in a wire) flows in a direction opposite to the change that caused it.</p>
<p>Do we need to know thermal expansion, like linear and volumetric expansion?</p>
<p>Yes we do, but the formula is rather simple</p>
<p>L(final) = L(initial) X coeff expansion x change in temp</p>
<p>Tito, does it not depend whether the flux is decreasing or increasing? On 47, the flux into the page from the right of A is decreasing, therefore the flux into the page from the left of B should increase. I’ve done the right-hand rule and the current would have to go downward on the left of B, therefore counter-clockwise, not clockwise as the book says.</p>
<p>I figured, usuing lenz’s law that since the loop is moving to the right and the magnetic flux is changing in that direction (which would be counter clockwise), the current would have to flow the opposite direction which is clockwise. I tried the right-hand rule on this one, and it told me that B was perpendicular to A of the second loop and so, as it moves flux would change at a maximum since it would be moving in parallel.</p>
<p>You can’t simply say, if the flux changes then the direction changes. B would have to provide greater flux into the page to its left. That is only possible if the current moves CCW. PR might be wrong on this one as well.</p>
<p>No, but the direction is opposite to that of the flux. I’ll look back at that one. But current is only induced in a wire (without another form of emf) if there is a change in the magnetic field or in other words flux.</p>
<p>I agree that the direction is opposite, but this creates a CCW current.</p>
<p>Does anybody know an easy way to remember when work is positive and negative and when Q is positive or negative in thermodynamics?</p>