# Temperature conversion

1. Jun 19, 2007

### scw287

1. The problem statement, all variables and given/known data

On the moon the surface temperature ranges from 371 K during the day to 1.09 102 K at night.
(a) What are these temperatures on the Celsius scale?
(b) What are these temperatures on the Fahrenheit scale?

2. Relevant equations
T=Tc+273.15 T=Kelvin temperature Tc=Celcius
9/5 F degrees/(1 C)

3. The attempt at a solution

I got both answers right for part a but for part b the answer solution says that my answers are incorrect.

What I did was first plugged in each temperature given in the problem separately into the equation to find celcius. I ended up with 97.85 C and -164.15 C which were correct! Then I used the second conversion 9/5 F degrees/(1 C) to find each of the temperature for farenheight using the celcius degrees answers from part a I got 176.13 degrees F and -295.15.
I think I worked this out correctly but the key says I'm wrong

2. Jun 19, 2007

### Staff: Mentor

There's an offset in the F temperature scale. Water freezes at 0C, but not at 0F. Does that help?

3. Jun 19, 2007

### cepheid

Staff Emeritus
You're forgetting that the zero points of the Fahrenheit and Celsius scales are not the same. More specifically, 0 degrees C is equal to 32 degrees F. As a result, you have to shift. I'll leave to you to determine whether to shift, then convert, or whether to convert, and then shift.

4. Jun 19, 2007

### scw287

Oops

So I need to subtract 32 degrees from each answer to take an account for the freezing pt.

5. Jun 19, 2007

### cepheid

Staff Emeritus
Not quite.

97.85 C means 97.85 Celsius degrees above freezing. When you convert these to Fahrenheit degrees, it means 176.13 Fahrenheit degrees above freezing, where freezing is 32 F. So...

6. Jun 19, 2007

### scw287

first i would take the celcius and subtract 32 degrees since its above the farenheight freezing pt. and then convert to farenheight by multiplying by (9/5)....right....and in the other part i would add 32 degrees since its below the zero pt??

7. Jun 19, 2007

### chemisttree

Both scales are equivalent at -40 degrees. Start from there and use the ratio you know. Be sure to readjust your answer to account for the 40 degrees.

8. Jun 19, 2007

### cepheid

Staff Emeritus
No and no. The conversion algorithm is always the same, and you have got it wrong. Think about it this way: How would you convert 0C to Fahrenheit?

EDIT: By the way, I was hoping you'd complete the thought here, that was the point of my post:

Last edited: Jun 19, 2007
9. Jun 19, 2007

### scw287

Man I was making this problem much tougher than it was! thanks for your help!

10. Jun 19, 2007

### scw287

o sorry, When you convert these to Fahrenheit degrees, it means 176.13 Fahrenheit degrees above freezing, where freezing is 32 F. so, Tf = (9/5)*Tc+32

11. Jun 19, 2007

### cepheid

Staff Emeritus
This is the exact point I was getting at, and the equation you posted above is the correct conversion formula! I'm glad you arrived at it by reasoning it out, that's what I was hoping to coax you to do!

12. Jun 19, 2007

### scw287

sometimes i just try to complicate problems...thanks for your help I appreciate it very much ;-)