<p>It was sooo tempting to say “use a ruler, DUH”</p>
<p>@garfield, i know i calculated the potential but put 0 for the field inside the sphere… that is correct?</p>
<p>For #5, when you had to find the mass m of the spheres, did anyone get a really small number, like 10^-15 or something? I just chose a point on the given graph and substituted it into the equation q=mgL/V to solve for m. And also, was the reason for the gap in the data is that the potential difference between 1600V and 2800 V or similar values would not cause the particle to move with constant speed? That was the only thing i could think of.</p>
<p>Is this calculator accurate? </p>
<p>[AP</a> Physics B Score Calculator - May 2011 Changes](<a href=“http://www.free-test-online.com/ap/ap_physicsb_score.html]AP”>http://www.free-test-online.com/ap/ap_physicsb_score.html)</p>
<p>^There’s more than one charge; you can only use that outside the sphere.</p>
<p>@cortana: yes, the field inside a conductor is zero. </p>
<p>For the gap, it’s because the charges would have to be between 1 electron and 2 electrons, which is impossible</p>
<p>well did you get a tiny number for the mass of the sphere, like 10^-15?</p>
<p>garfield, do you remember if the electric field question was to find the electric field from 0.2 or whatever from the center? would it still be zero? why would plugging it into kQ/(r +distance of point)^2 be wrong?</p>
<p>@ cortana, i did too.</p>
<p>could you have used w=fd instead of finding the change in the kinetic energy to find the net work over 3.s</p>
<p>Since 0.24 is greater than the radius, you do use that formula.</p>
<p>I don’t remember the mass, but 10^-15 is not unrealistic since they’re small particles</p>
<p>aa2011, that is what I did!</p>
<p>Yeah, I remember that q was 1 electron charge and V was 3000, and L was 0.05. That gives about 10^-15</p>
<p>I took ap physics right after ap bio and my brain was not functioning properly. Ill be happy with a 3. But I feel so bad for doing poorly on the exam.</p>
<p>@garfield, thanks for the clarification! then where are you guys saying would the elec field be zero? was it that same frq?</p>
<p>aa2011, thats what i did too! found acceleration, times mass = force, multiple by area under the graph from 0 to 15 sec.</p>
<p>^I did the same thing; good thing Bio was so easy</p>
<p>Oh well, im in the bargaining stage of grief. Im praying for a 3.</p>
<p>i was really looking forward to an optics and/or thermodynamics question on the FR.</p>
<p>@squigglysquid: It’s zero inside the sphere and kQ/r^2 outside, where r is the distance from the center.</p>
<p>A thermo question would have been really nice</p>
<p>Can you take the same exam twice, tell my coordinator to order late testing?</p>
<p>aa2011: I don’t think you can</p>