Recent content by cheez

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    Understanding d and Δ in Integration

    How come d becomes (delta)? after integration? I thought d and delta is the same thing. What's the difference between them? For example, dA = - PdV After intergration, it becomes (delta)A = -(integral)PdV I can't type the symbols. thx!
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    Volumetric thermal expansion coefficient

    http://farm1.static.flickr.com/122/367693621_f74963f0ea_o.jpg" I've taken the derivative and substituted beta and k? into it. How to make it looks like step 6? thx!
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    Volumetric thermal expansion coefficient

    Actually it's a math question. Can I cancel V from both side in step 3? thx!
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    Minimun lens size (in meters) that will permit just resolving 2 stars

    thx for your answer!
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    Minimun lens size (in meters) that will permit just resolving 2 stars

    how to calculate theta? thanks you so much!
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    Minimun lens size (in meters) that will permit just resolving 2 stars

    I have really no clue on how to this:cry: please help!
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    Calculating Proton Energy for a Large Cyclotron Using Earth's Magnetic Fields

    Some misunstanding is here. Sorry about that. The answer my teacher gave is 1.56 x 10^13 V. I can't get the same answer as my teacher from the calculation above.
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    Calculating Proton Energy for a Large Cyclotron Using Earth's Magnetic Fields

    The anwer doesn't have unit. (This is the sample test from my teacher, he doesn't type units for answer.) But in the question, it said volts. The unit I got is Newton x Seconds/ kg. Actually, I don't know how to make it into volts. I don't even know if it's the right method. :(
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    Calculating Proton Energy for a Large Cyclotron Using Earth's Magnetic Fields

    The answer is 1.56 x 10^13 I can't get the answer. Fm = F centripetal Force qvB = mv^2/r v= rqB/m Calculate energy KE = 1/2 mv^2 I put in v = rqB/m KE= 1/2 (rqB)^2/m I plug in all the #, but still can't the answer please help, thanks so much!
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    Why Does an Aluminum Ring Levitate Above a Magnetic Coil?

    I don't know how to answer these questions. :( I know the alternating current makes the magnetic field changes. And the changing magnetic field generates emf.But I don't know why the emf is large enough to push the aluminum ring upward, and how come it goes up? thx a lot.
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    Centripetal force equation help

    no, I have typed the whole question.
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    Centripetal force equation help

    v= r x omega = (39 ft) x (0.022 rev/s) x ( 2 pi / 1 rev) =5.391 ft/ s mu x m x g = m x v^2 / r mu x g = v^2/ r (0.36) (32 ft/s^2) = (5.391 ft/s) ^2 /r r= 2.5 ft but the answer if 15.7
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    Centripetal force equation help

    I have set up an equation like this: v= r x omega mu x m x g = m v^2 /r but I didn't get the answer, which is 15.7. Is the setting right? If not, can anyone show me the right steps? thx!
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    How high will the hand glider pilot rise with this energy conservation problem?

    I want to know what's wrong with my steps, because I don't get the answer. The answer is 33.8m
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    How high will the hand glider pilot rise with this energy conservation problem?

    ps:work done on friction.