How do you convert temperature differences between Celsius and Kelvin?

[lizlyn]

Homework Statement

The temperature difference between the inside and the outside of a home on a cold winter day is 57.0°F.

express in C and in K

Homework Equations

Tf = (9/5) delta Tc
Tc = Tk - 273.15

The Attempt at a Solution

I used the first equation to find that the temp difference in C is 31.67
I then thought that you added 273 to that temperature to find Kelvin but on my homework the answer key said that the correct answer is 31.67K ... i don't understand how the two can be equal?

 

[NobodySpecial]

The size of a kelvin and the size of a degree C are the same (by definition) they are only different in where you start counting from

If you are measuring a temperature difference does the zero point of the scale matter?

 

[Borek]

Tf = (9/5) delta Tc

That's to convert changes in temperature between Celsius and Fahrenheit scales.