<p>^ is it A?
If not, tell me how to do it please, lol.
I hate pendulums and oscillations SO MUCH.</p>
<p>T=2pi<em>sqrt(L/g)
1=6</em>sqrt(L/10)
(1/6)^2 *10 = L
L = .16^2 * 10 = .25m</p>
<p>g at 2(radius of earth) is 2.5m/s^2 so
T=6sqrt(.25/2.5) = 6sqrt(.1) = 6(approx 1/3) = 2seconds</p>
<p>Answer: C</p>
<p>That took way too long to figure out and I’m probably wrong.</p>
<p>No, not A. Not C.</p>
<p>Remember: MC, no calculators!</p>
<p>What, why not?
Gravitational force decreases as you move away from the Earth (2r) and if g decreases, T increases (since g is in the denominator in the square root, T increases by a factor of 2^2 = 4)!</p>
<p>That is a completely flawed reasoning, isn’t it?
I’ll say B then.</p>
<p>Alright, I guess B then.</p>
<p>Are we allowed an equation sheet for the MC?</p>
<p>i got C. answer is 2?</p>
<p>I got C, 2 seconds…</p>
<p>well, Fg =Gmm/r^2, and the distance is x2, so Fg = 1/4 g</p>
<p>t= 2pi sqrt(L/G), where g = 1/4g</p>
<p>–> t = 2pi sqrt(4L\G) where sqrt(4) = 2</p>
<p>1:2 ratio? :(</p>
<p>Ah, I think I got it:</p>
<p>Its at an elevation of two earth radii from the surface of the Earth.
So, the total distance that its away is (r + 2r) = 3r.</p>
<p>Now, F = Gmm/r^2, F = 1/9th of g.
So T = sqrt.9 = 3.
Its B.</p>
<p>Correct?</p>
<p>marc, in my mock ap i was given a formula sheet but it was pretty much useless. with 35 mc in 45 minutes, you really need to go off of memory and first instinct.</p>
<p>Axeback, I think you are correct. Seems logical to me!</p>
<p>Lets confuse ourselves even further:</p>
<p>An asteroid moving at constant velocity in space suddenly explodes. How many of the following quantities remain constant throughout and after the explosion?</p>
<p>I. The kinetic energy.
II. The momentum.
III. The position of the center of mass.
IV. The velocity of the center of mass.
V. The angular momentum of the asteroid system.</p>
<p>a) none
b) one
c) two
d) three
e) four</p>
<p>angular momentum is conserved b/c there is no outside torque. linear momentum too probably b/c there is no outside forces. not sure about other 3</p>
<p>i doubt KE is conserved though, b/c there must be some heat unless it is perfectly elastic</p>
<p>lol dang it this thing is on Monday isn’t it.</p>
<p>I’m self studying it as well 
my only problem? I started studying at 3 PM this afternoon…</p>
<p>Less than 2 days of studying an entire Physics course! Oh joy… I’ll pass both though, possibility of a five on mechanics I hope… I’m not through the PR book though for even Mechanics yet (I just got through rotational motion…)</p>
<p>Can anyone please inform me how to grade my AP practice tests?</p>
<p>Princeton review says that a 75% or higher raw score gives you a 5… I find this highly unreliable…</p>
<p>What do you need for a 5 on the Mechanics?</p>
<p>What do you need for a 5 on Electricity?</p>
<p>How is your score determined (All I know its 50/50 between MC and FR, but it’s out of 90? So each section is 45… With 35 MC… and 3 FR… What do they multiple things as and what is each FR worth)</p>
<p>Each FR is worth 15 pts (and there are 3), each MC one point.
Thats out of 45 + 35 = 80.</p>
<p>+53 is a 5, +37 is a 4.
Yep, fairly lenient curve.</p>
<p>You get 45 mins for both sections btw (I still feel we need an hour atleast for MC).
(same applies to E&M).</p>
<p>Sir not to be rude but: [AP:</a> Physics C](<a href=“AP Exams Calculator Policy – AP Students | College Board”>AP Exams Calculator Policy – AP Students | College Board)</p>
<p>Says that each section is worth 50%… And you said mult. choice is weighted less</p>
<p>Yes…50% in MC and 50% in FRQs…you get 45 mins for each.
Even though there are only 35 MC questions, its still 50% of your final score.</p>
<p>The # correct - (1/4)#wrong = raw MC score–> MCscore x 1.2857 = MC total score</p>
<p>MC total score + points/45 on FRQ = final composite score / 90</p>
<p>usually, 50/90 is a 5, give or take 3-ish points</p>
<p>Thank you user3725. Axeback, you said that the Multiple choice was worth 35/80, while the free response was the other 45/80, which would imply that free response is worth more points. You also said 53/80 is a five, a big difference from 53/90.</p>