# Homework Help: Two water tanks

1. Jul 17, 2012

### 5carola5

1. The problem statement, all variables and given/known data
There are two tanks with water, there are standing very close to each other. Tank 1 is having a temperature of 0 degrees and tank 2 is having a temperature of 10 degrees. The heatflow between the two is Q1. Then tank two is getting a temperature of 100 degrees. That heatflow we will call Q2. The question is: By what degree will the ratio Q2/Q1 chance?

2. Relevant equations

I don't know really...

3. The attempt at a solution

So I used Q=cA(T14-T24). c and A are some constants that are the same for both tanks so cA=C. Then I put the temperatures in the formula making it:
Q1=C*104 and Q2=C*1004 Then deviding them to get: 1004/104=1*104 (the constant C disappears). So my answer would be 1*104 And the answer is supposted to be 16, which sounds much more normal to me. But I have no idea how to get here...
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jul 17, 2012

### TSny

What unit should you be using for T?

3. Jul 17, 2012

### 5carola5

celcius, sorry forgot to say

4. Jul 17, 2012

### TSny

Is it ok to use Celsius unit in the formula, or does the formula require that you use another unit?

5. Jul 17, 2012

### 5carola5

I don't really know extally, can try to do it in Kelvin as the last time I did it in celsius... lets see.

then it becomes: (373^4) / (283^4) = 3,018. That's also not alright, so it must be something else. Might be a total differend formula, I really don't know...

6. Jul 17, 2012

### TSny

Did you also convert the 0 oC to Kelvin?

7. Jul 17, 2012

### 5carola5

aaaah I forgot ^^'
((373^4) - (273^4)) / ((273^4) - (283^4)) = -16,1... Oke thanks a lot ^^" That was pretty stupit of me... But I will not do that wrong again for quite some time :P

thanks again:)

8. Jul 17, 2012

### TSny

We've all learned that lesson the hard way.