<p>For preparing before the actual exam.</p>
<p>Well... I'll be the first to post something... What is everyone doing for last-weekend studying? I'm trying to memorize the reference table for the multiple choice section.</p>
<p>For me, I am reviewing nuclear physics and practicing with the old exams (2004 and 1993 so far). Memorizing the table also helps.</p>
<p>Nuclear I know pretty well from AP Chem... It's electromagnetics that kills me. We practiced a lot of Part 2s in class, and 3 multiple choice exams: 2004, 1993, and 1984 I think...</p>
<p>^^ Electromagnetics is my killer too.</p>
<p>Yeah... We must have gone over Lenz's Law 20 times, and I still always mess it up... My teacher said the best advice is that it's almost always counterclockwise on the tests for some reason</p>
<p>I'll be in the chat room all day if anyone needs help.</p>
<p>how do I access the chatroom?</p>
<p>bump .</p>
<p>I think this is what is meant by chatroom... unless I'm wrong</p>
<p>Please help me on these objectives:</p>
<p>Determine whether entropy will increase, decrease, or remain the same during a particular situation.</p>
<p>Relate the heats exchanged at each thermal reservior in a Carnot cycle to the temperatures of the reserviors.</p>
<p>Thanks</p>
<p>Umm entropy is just the disorder of the system... more of a chem thing... cant help unless u mention the specific situation i dont think... and i still think the thing on the Carnot cycle is what i said in the other thread...</p>
<p>entropy of the universe is always increasing unless you are at absolute zero which isn't possible. </p>
<p>entropy of carnot engine is 0 and it's true for any other reversible process..</p>
<p>Im not sure if you need the formula or not but for a reversible process S(entropy) = Q/T (constant temperature) and there's another pretty looking formula involving ln and what not when temperature is not constant.</p>
<p>entropy isnt exactly always increasing... i guess maybe for physics... but there r processes like chemical equations where things become more ordered or the entropy decreases</p>
<p>Hmm.. well the entropy of the universe is always increasing (that's what i learned)...a reversible system can have decreasing entropy if it cools down or something..</p>
<p>That's the extent of entropy we have done. I think that's all for physics..</p>
<p>Ok, I've read more about entropy and your guys's posts and I think I understand entropy now. How come the entropy of a carnot cycle=0??</p>
<p>Also, I don't get how "refrigerators" work. I mean it is the opposite process of heat engines so it takes the heat from the cold reservior to the hot reservoir with the help of work?? How does hot heat coming in refigerate things? Wouldn't it be like a heater then? lol</p>
<p>Wait, I think I'm getting confused with Q(Cold) and Q(hot)..</p>
<p>yea i think ur right... id just go by that for physics... we didnt really do anything with it in physics... i just kno about it from chem.</p>
<p>my notes say entropy of a carnot engine is 0. Dunno if it's important or not..Oh well...I should probably stop confusing myself now</p>
<p>I think a carnot engine would be optimal efficiency, so there would be no decrease in order. Hence, entropy would be zero.</p>
<p>bump please join</p>