<p>It’s a slight modification of the formula used to find the position of the CM
SUM(MiXi)/SUM(Mi)
Remember, as my phys teacher used to say, if you can calculate your grade, CM stuff shouldn’t be hard to find. Also, be sure to check your units. You know the VMC formula works because the kg units on top and bottom cancel and you’re just left with m/s. Similar situation with Xcm</p>
<p>1.b) ii.
<a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board;
<p>If you used the data points would you not get credit?
I know in some problems they require you to use data, and now they don’t? How can you tell which they want? I think the wording is the same too, if I remember correctly.</p>
<p>Also bringing attention to my question on the previous page:
Would they just mark the first, incorrect one?</p>
<p>I am guessing it’s enough that you merely filled the chart in with the correct data values, given CB is trying to be more lenient nowadays. Interestingly enough though, the '06 exams I was looking at earlier today devoted a point to plotting the data. Nonetheless, it’s probably better to be safe and plot the points.</p>
<p>CB also started giving points for consistency. Let’s say you did not notice your mistake in part a for example. So long as you are consistent and avoid making further mistakes, you do not get the point in part a, but you get the point(s) in the parts of the question dependent upon the answer given in part a.</p>
<p>Yes, a lot of the past ones give multiple points for graphing.</p>
<p><a href=“Supporting Students from Day One to Exam Day – AP Central | College Board”>Supporting Students from Day One to Exam Day – AP Central | College Board;
<p>2.d)
Why aren’t you supposed to do conservation of energy first, to get the additional gravitational potential energy and solve for the new, final velocity before impact (which I got to be 9.4 m/s) and then use conservation of momentum?</p>
<p>I get what you’re saying now. IDK why they didn’t account for it or at least make a footnote.</p>
<p>2004 #8) A sphere of mass m, radius r, and rotational inertia I is released form rest at the top of an inclined plane of height h. If the plane has friction so that the sphere rolls without slipping, what is the speed v(cm) of the center of mass at the bottom of the incline? </p>
<p>The answer is square root[2Mgh(r^2)/ I + M(r^2)], can someone show how to arrive at this answer?</p>
<p>Grav. Pot. = KE + Rolling KE
mgh=0.5mv^2+0.5Iw^2
…=0.5v^2(m+I/r^2) w = v/r
2mgh/(m+I/r^2) = v^2
multiply through by r^2
2mgr^2/(mr^2+I) = v^2
now sqrt it</p>
<p>crud… I am not sure how I will do tomorrow. I really really hope I get at least a 3… I need to review SMH/oscillations… oh and graphs… I am stuck on graphing. I did 1993 E&m free response and the only question i got was the last one…</p>
<p>Does anyone have list of important graphs to memorize?</p>
<p>@TheMmysteriousOne, thank you :)</p>
<p>no prob RAD
As for neorobie, check out a couple MIT vids.
[MIT</a> OpenCourseWare | Physics | 8.01 Physics I: Classical Mechanics, Fall 1999 | Video Lectures](<a href=“http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/]MIT”>http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/)</p>
<p>ahh time is running down</p>
<p>As for graphs, i don’t think you will be making much use of those. If you know the equations and some basic calc principles, your intuition will take care of the rest.</p>
<p>ahhhhhhhhhhhhh</p>
<p>“A student initially stands on a circular platform that is free to rotate without friction about its center. The student jumps off tangentially, setting the platform spinning. Quantities that are conserved for the student-platform system as the student jumps include which of the following?
I. Angular momentum
II. Linear momentum
III. Kinetic energy”</p>
<p>Why is it only angular momentum?</p>
<hr>
<p>And #19:
<a href=“AP Physics C Mechanics Practice Tests - 百度文库”>AP Physics C Mechanics Practice Tests - 百度文库;
<p>And why isn’t 27 B? Shouldn’t it have 0 slope because it’s conserved?</p>
<p>&& 28, 29, 32, 34.</p>
<p>Are princeton review tests harder than the real test? Cause it seems a good amount harder than the released tests.</p>
<p>@Abrayo is that a real test, where is it from?</p>
<p>^^ No idea, sorry.</p>
<p>@etennis12:
Not sure, someone posted it here earlier.
I failed it.</p>
<p>Guys, this is what we should all do:
Right before sealing your multiple choice thing/after putting your pencil down and waiting for instructions, look for patterns in your answers so that we can discuss them! (ex. 4 Cs in a row, etc).</p>
<p>That’s allowed, right? Since we’re not talking about the problems?</p>
<p>I answered 27-28 earlier</p>
<p>Anyways, do u kno if the princeton review tests are harder? ANyone?</p>
<p>Hmmm so yeah, I’m stuck on one (anyone wanna help?):</p>
<p>[Image</a> - ■■■■■■■ - Free Image Hosting, Photo Sharing & Video Hosting](<a href=“http://■■■■■■■.com/r/11k8qhk/7]Image”>http://■■■■■■■.com/r/11k8qhk/7)</p>
<p>
</p>
<p>Yeah, I sent it to him. MC was a bit weird.</p>