Linear Thermal expanion what is the formula we use?

[Idrees]

Linear Thermal expanion! what is the formula we use?

Homework Statement

I have been given a linear coefficient which 1.2*10^-5 of something
i have been given the initial temperature of 30 degrees and final temperature of 55 degrees
I have been given that initial length is 3.0 m

I am trying to find the unknown final length ?

Homework Equations

please what's the relevant equation i need to use

The Attempt at a Solution

 

[rock.freak667]

try $extension=L\alpha T$

 

[Idrees]

im sorry which one is extension

i used one forumula and i got 50

it was Final lenght= a Lenghts (final temp -initial temp) + initial lenght
thus final length = 2.0 m (initial lenght) *( 45 deg-20 deg) + 2.0 m
= 50 meters

is this right approach ?

 

[rl.bhat]

In then problem the initial length is 3 m.
The relevant equation is
Lf = Li( 1 + alpha*change in temperature) where alpha is the coefficient of linear expansion.

 

[Idrees]

thank you for that