AP Physics B

<p>8...it was number of people * mass of person * g = Bouyancy force of water on raft when raft is fully submerged. N came out to be 8.4, and so 8 people.</p>

<p>Sorry for double posting...on the mols of gas problem, did people get around 2.01 mol?</p>

<p>did u use linear regression to find an equation? to find part a( the relationship)</p>

<p>Yea. i got 8 people as well... on last question, Did you guys get a frequency like something E 15, like UV or somehting?...Part D, i pulled out of my @ss, come to think of it Work/q equals V.. damn.....what did u get for the tension on string and velocity on the simple pendulum....and was the Point charge question equal to somehtign like Fe = k q2q / r^2? I used a cheat formula for the lab x/l = wavelength/ d...it only works for small angles when sin@ approx equals <a href="mailto:tan@...hope">tan@...hope</a>fully i get some points</p>

<p>i got 1.2 moles and 15 people</p>

<p>i got something like 1.6 moles also</p>

<p>hm... here's a question for you guys. On the AP frq equation sheet, it says E_{avg}=-V/d
but on the Princeton Review, it says \delta V=Ed
I know I am missing something here.</p>

<p>Right, if V=Ed, then E=V/d :-P. Math, here. The negative sign comes purely out of convention.</p>

<p>how did people solve for the h in part a?</p>

<p>The negative sign is what confused me. What do you mean that it "comes purely out of convention"?</p>

<p>Mole was 1.2 b/c you have to put 1 atm in pascal.</p>

<p>the - is for direction not used in calculation of magnitude.</p>

<p>It depends on whether you define the energy of a positive particle to be positive or negative, which in turn depends only on the way you orient your axis, and the mood you're in on any certain day. I've seens grader's comments on past AP's, and usually they completely ignore whether or not your answer is negative or positive, because it depends so much on convention. Unless you get a negative kinetic energy or something...like me, in problem 7...'-_-</p>

<p>ahhh, thank you very much.</p>

<p>ii got 1.2 and 8 people as well...</p>

<p>hoping for a 5.. and if 60% gets a 5.. i dont see any reason why i didnt get that.. the MC was similar to the SAT II, which i got an 800 on... the free response was harder for me b/c my teacher didnt prepare us well... but I think i nailed 3 or 4 of the 7 questions and got several points on the others</p>

<p>can someone explain how they got 8 for the ppl?</p>

<p>How, may I ask, does one find the height out of the water of the raft? I got .08 m, and 10 people.</p>

<p>But I DID get 1.2 moles.</p>

<p>what were they looking for in "Describe the measuring process." in lab question? I just said take meter stick and measure L, use light intensity meter to see where the bright fringe's at, and use ruler to measure distance b/w two adjacent bright fringes.
Is that sufficient?</p>

<p>yea thts wht i did</p>

<p>number of people * mass of average person * g = bouyant force.
Bouyant force= volume of water displaced * density of water *g.
volume of water displaced=volume of raft, since raft is submerged to maximum, since it is holding the maximum number of people.
g cancels out.
Hence, number of people=density of water * volume of raft/average mass of person.
I don't remember the volume of the raft, but it should come out to a little above 8 (The volume should have been like 0.6 m^3)...err...that number doesn't seem too familiar...oh well, maybe my memory's just playing tricks.</p>