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Homework Help: A Tricky exponetial problem

  1. Oct 13, 2008 #1
    Can anyone help me with this problem???

    1. The problem statement, all variables and given/known data
    Supposed A=BnCm, where A has dimensions LT, B has dimensions L2T-1, and C has dimensions LT2. Then the exponents n and m have the values:

    a. 2/3; 1/3
    b. 2; 3
    c. 4/5; 3/5
    d. 1/5; 3/5


    2. Relevant equations
    N/A


    3. The attempt at a solution
    Tried to set up the equation as below:
    since:
    A=BnCm
    so,
    LT= L2T-1*LT2
    I don't know what to do next?
     
  2. jcsd
  3. Oct 13, 2008 #2

    cristo

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    Staff Emeritus
    Science Advisor

    You didn't set your equation up correctly. If B has dimensions L2T-1, then Bm has dimension (L2T-1)m.
     
  4. Oct 13, 2008 #3
    Oh, I found the answer!!! It's (d). I just have to try to substitute each choice into the equation to find the right answer. ^^Thanks a lot.
     
    Last edited: Oct 13, 2008
  5. Oct 13, 2008 #4

    Mark44

    Staff: Mentor

    But what if this were a problem on a test, and you weren't give the answer? Your technique wouldn't help you any. Cristo has given you a good start.
     
  6. Oct 13, 2008 #5
    hihihi. Yes, he you're right! However, I thought, if they don't give us the answer,they will at least give us the value of either n or m, or the ratio b/t these two variables in order to solve the equation. Thanks for your comment, Mark. You have a nice day!
     
  7. Oct 14, 2008 #6

    HallsofIvy

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    The question is do you know how, by following cristo's comment, to find m and n even if you aren't given possible answers?
     
  8. Oct 20, 2008 #7
    Thank you all!
     
  9. Oct 21, 2008 #8

    HallsofIvy

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    Science Advisor

    Do you understand that I asked a question?


    You have not yet answered my question.
     
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