Question

The length of a steel beam increases by 0.78 mm when its temperature is raised from 22 degrees C to 35 degrees C. What is the length of the beam at 22 degrees C (in meters)?

Answer 1

`l_0=4.545m`
I may be wrong but I think you need something else...the expansion coefficient perhaps...?

Explanation:

You can use the expression that describes thermal linear expansion as:
`Deltal=l_0alphaDeltaT`
Where:
`Deltal=l-l_0=`change in length;
`l_0=`original length (at 22°C);
`alpha=`expansion coefficient;
`DeltaT=`change in temperature.
In your case:

`0.78/1000=l_0*alpha*(35-22)`

From the litterature you have:

With the data you have and the coefficient from the table:
`l_0=4.545m`