Question

3) An aluminum bar and a steel bar at both 4.2 meters length at 20 degrees Celsius. What will be their new length when both of them are heated to 170 degrees of Celsius? If this was a bimetallic strip, at which direction would it bend to.

Answer 1

Linear expansion coefficient of aluminium bar is

And for steel it is

​so change in length due to thermal expansion we write

​​​​​​

So T_2 = 170°C

T1 = 20°C we get

Lf = 4.2138 m

Similarly for steel

We get,

Lf = 4.20693 m

So as we can see change in length of steel is less than aluminium so bimetallic strip bend toward steel.