# Expansion of steel railway

1. Jul 10, 2016

### martinbandung

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

The steel railway will be constructed in a place that temperature can change 8°C. Length of each rail is 10 m. With α=11*10^-6 . Minimum space required between the rail is...

2. Relevant equations
ΔL= L0 α Δt

3. The attempt at a solution
I confuse wether i should multiply it by 2 or not. Where does the expansion go (direction). Is it only to one or two direction (left or right)?

2. Jul 11, 2016

### haruspex

The expansion does not have a direction unless you nail one end in place. It is just a change in overall length.

3. Jul 11, 2016

### CWatters

Apply the same rule to the sections of track either side of the one you are considering. You will find it makes no difference...

If it goes "one way" then the increase in length encroaches into one gap (the other end is fixed).

If it goes two ways half the increase in length encroaches into two gaps (one each end) but then the same applies to the sections either side. So again one increase in length encroaches into one gap.