Question

In the linear thermal expansion, should L be the final length, initial length or does it matter?

Answer 1

ΔL = L*k*ΔT

Δl = change in lenght (NOT change + initial lenght)
L = total lenght BEFORE expansion
k = coefficient of expansion (sometimes also written as alpha)
ΔT = temperature differance
This equation only gives you how much expnasion has happend.


You can also wirtte it like this:
L = L' (1+kΔT)

L' - initial lenght
L - lenght after expansion
This one adds the expansion to the initial lenght as an output

Answer 2

@Mate.j why should the L be the initial length?