<p>Haha… I am feeling so stupid today. Could anyone help me with what is probably an easy question?</p>
<p>It’s from the AP Physics 2003 exam…</p>
<p>You have a 100 kg box, it’s sliding across a rough surface and its position x varies with time according to the equation x=0.5t^3+2t</p>
<p>What is the net work done on the box in the interval t=0 to t=2?</p>
<p>Thanks…</p>
<p>take derivative to find v then use 1/2mv square - 1/2 mv square? damn. i cant believe i’m still sober after getting deferred…</p>
<p>I’m taking a test on this s*** tomorrow!</p>
<p>wouldn’t u just find the displacement using that equation and multiply it by 980?</p>
<p>Is that a related rates problem? We did them in calc…I hate related rates…</p>
<p>mgd= W</p>
<p>tm2000 is on the ball. That’s the correct way, good job. Work done by weight.</p>
<p>lol thanks guys… i hate related rates… i have a test on it tomorrow…</p>
<p>i couldnt do the hw cause the problems were so difficult… so instead… i flew through all the next 9 hw assignments meaning im set till the end of the semester (usually about 3 assigned / wk… long assignments thoughh… like 30-40 problems / assignment)</p>
<p>i love physics…my teacher is the s***</p>
<p>it says rough surface…so arent we supposed to assume some kind of friction…must not be though cause they would have to give you a mu value…or are you supposed to assume its so rough mu is nearly one and therefore the frict. force is about equal to Fnet…never seen that before though…lol I hope Im not sounding stupid here</p>
<p>I may not be able to get into PENN, but at least I can do AP Physics :].</p>