# Homework Help: Expansion of metal (heat)

1. May 15, 2015

### goonking

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

2. Relevant equations
ΔL = α L0 ΔT

3. The attempt at a solution
I converted the 0.62 mm to meters, giving 0.00062 m

am I suppose to convert the degrees from Celsius to K? why is the coefficient for steel in K-1? What does that even mean?

anyway, I converted C to K and answer I got was my initial length to be 0.180 meters

Last edited: May 15, 2015
2. May 15, 2015

### Orodruin

Staff Emeritus
0.00062 m

You are dealing with temperature differences, not absolute temperatures. The temperature difference has the same numerical value in the Kelvin and Celsius scales, i.e., for temperature differences 1 K = 1 °C. When absolute temperatures are involved, it is essentially always necessary to use Kelvin unless an expression has been specifically tailored to the Celsius scale. In physics, Kelvin is a more natural scale than Celsius as it has zero at absolute zero.

And again, do not confuse C with °C (or ° C, which has no meaning, for that matter ...).

3. May 15, 2015

### physicsmama

The coefficient for expansion means that steel expands 1.2 parts in 100,000 for each 1 Kelvin increase in temperature. A change of one Kelvin and one degree Celsius is the same, so you actually don't have to convert in this instance. Kelvin is a standard temperature scale used by the scientific community. Many tables of the coefficients of expansion for different materials are given in Kelvin, so that is probably why it was used.