# Homework Help: A Tricky exponetial problem

1. Oct 13, 2008

### iconwin

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. Oct 13, 2008

### cristo

Staff Emeritus
You didn't set your equation up correctly. If B has dimensions L2T-1, then Bm has dimension (L2T-1)m.

3. Oct 13, 2008

### iconwin

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
4. Oct 13, 2008

### 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.

5. Oct 13, 2008

### iconwin

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!

6. Oct 14, 2008

### HallsofIvy

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?

7. Oct 20, 2008

### iconwin

Thank you all!

8. Oct 21, 2008

### HallsofIvy

Do you understand that I asked a question?

You have not yet answered my question.