<p>I think the most important thing to do is to memorize every equation on the formula sheet (speaking of the formula sheet, we actually get one more equation than the past students did: Density=Mass/Volume). Since there is no calculator allowed on MC, many questions will ask on how changing a value by a certain factor will affect another factor (e.g. double the pressure results in the volume being multiplied by what factor, etc.).</p>
<p>Some derived formulae not on formula sheet<em>can be made by formulae found on there tho</em>:</p>
<p>Thin-film interference:
both beams undergo phase change-
2t=m(lambda) constructive int
2t=(m+1/2)(lambda) destructive int</p>
<p>only one beam undergoes phase change-
2t=(m+1/2)(lambda) constructive int
2t=m(lambda) destructive int</p>
<p>Torricelli’s theorem:
Velocity(upon leaving hole)=sqrt(2g[delta y]) (Assuming p1=p2 as part of bernoulli’s)</p>
<p>For glass prisms:
theta 3(angle of incidence for glass->air) = 60 - theta 2(angle of refraction for air->glass)</p>
<p>I still don’t understand why the give us the equation sheet when doing the FRQs, but not the MC!</p>
<p>do you get full credit for the FRQ, when you simply use Torricelli’s Theorem instead of Bernoulli’s Equation? (Assuming that Torricelli’s is perfectly applicable)</p>
<p>^ if it can be solved with Torricelli then yea you can use it.</p>
<p>is it allowed to put notes on a ti-89 for free response bcuz i just put like everything you need to know for magnetism on it…</p>
<p>oh oh yes… i forgot, can you use range formula
R = v^2 sin (2*theta) / g without deriving it?</p>
<p>how do you find the momentum of a photon (yea I know there massless so p=mv doesn’t work, but some other formula does)…</p>
<p>de broglie’s equation i guess</p>
<p>yes for high energy particles that are very small
lambda = planck’s constant divided by momentum and derive momentum from that equation. but note that de Broglie’s does not apply in macro scale, but only to very small particles. (i.e. electron, photon, etc)</p>
<p>btw, what is the definition of “rest energy?”</p>
<p>if a question is asking you for work done by a gas, and i use the equation -P(change in V) to get a negative number (lets assume -3000), shouldn’t the answer be +3000 J because that equation is for work ON a gas?</p>
<p>Princeton is telling me it’s -3000 still. could somebody please explain this to me?</p>
<p>Depends.
Case (1)
dU = dQ + dW, on the gas
W (on the gas) = -P dV.</p>
<p>Case (2)
dU = dQ - dW, by the gas
W (by the gas) = P dV</p>
<p>and I do not really understand ur question. Write it in a more complete way pls?</p>
<p>the - is only when work is done BY the gas.
if its done ON you just discard the negative. it’s a vector equation so the negative is a directional thing (sort of)</p>
<p>for questions that deal with planets and their radius and acceleration due to gravity these are the only formulas that i could think of that would work:</p>
<p>Fg=mg
Fg=Gm(1)m(2)/r^2</p>
<p>whenever i try to use these formulas to solve questions like this one:
A new planet is discovered that has twice the Earth’s mass and twice the Earth’s radius. On the surface of the new planet, a person who weighs 500N on Earth would experience a gravitational force of
a.) 125N
b.) 250N
c.) 500N
d.) 1000N
e.) 2000N</p>
<p>any other formulas that you may know that can help with these kinda problems are much appreciated.</p>
<p>yeah, that’s what i thought, but the answers in the Princeton include the negatives so i was a bit confused.</p>
<p>Is the answer B, 250N?</p>
<p>dont ever memroize whether work is goin to be negative or positive, especially when on the ap exam the gas might be doing the work or it might be getting the work done on it.
you just have to use ur logic and determine if it gains energy from the work or looses it from work, and then add a sign depending on if it asks done on or done by the gas
kinda hard to explain.</p>
<p>is that B? 250</p>
<p>That is a B for sure. I am 100 per cent positive.
remember that g, planet =GM, planet/r^2. this means that if radius is doubled and mass of the planet is doubled, the overall change is a factor of 1/2. therefore u should weigh 250 N which is half of 500 newts. (i suck at puns :))</p>
<p>how many wrong on ONLY the mc choice for PR would still let me get a four?(assuming i get average scores on FR like 7/10 and 12/15 or so )</p>
<p>i think it’s B, though plugging in something in Newtons for mass is making me a little nervous…
and the Ug of gravity away from Earth’s surface is Gm/r^2, so maybe you have to use that? not sure, I feel like this question should be easy, but there are always little tricks…</p>
<p>Yeah the answer is B.</p>