# How do I convert BTUs to calories?

1. Mar 2, 2015

### Eclair_de_XII

1. The problem statement, all variables and given/known data
"The use of the British thermal unit (Btu) is common in much engineering work. A Btu is the amount of heat required to raise the temperature of 1 lb of water by 1°F. Calculate the number of joules in a Btu.

2. Relevant equations
"A calorie was originally defined as the amount of energy required to raise the temperature of 1 g of water from 14.5°C to 15.5°C. A calorie is now defined in terms of the joule:

1 calorie = 4.184 J"

3. The attempt at a solution
I know one BTU is 1054 J. Here is what I believe to be correct:
1-lb(453.59 g/lb)(4.148-J/1°C)(5/9°F/1°C) = 1054 J
However, I'm a bit worried about my last factor. Isn't it supposed to be (5/9(°F - 32°)/1°C)?

2. Mar 2, 2015

### Staff: Mentor

No. You are that there are 9/5 Fahrenheit degrees per °C, and you are not interested in where the scale starts.

3. Mar 2, 2015

### SteamKing

Staff Emeritus
If 1 calorie = 4.184 J, and 1 BTU = 1054 J, why are you fiddling around with these other extraneous calculations?

4. Mar 3, 2015

### Staff: Mentor

My understanding is that he has to convert using only the data given.