Question

A strip of copper metal is riveted to a strip of aluminum. the two metals are then heated. the coefficient of linear expansion of aluminum is greater than that of copper. what happens?

Answer 1

When a copper strip is riveted to an aluminum strip and then heated, the aluminum portion will expand more due to its greater coefficient of linear expansion. This unequal expansion causes the strip to bend towards the side of the aluminum.

Step-by-step explanation:

When a strip of copper metal is riveted to a strip of aluminum and then heated, the two metals will expand due to the increase in temperature. However, the coefficient of linear expansion of aluminum is greater than that of copper. This means that aluminum will expand more than copper for the same increase in temperature.

As a result, when the strip is heated, the aluminum portion will expand more than the copper portion. This unequal expansion will cause the strip to bend towards the side of the aluminum, creating a curvature (as shown in Figure 13.3). The strip will bend in the direction of the metal with the higher coefficient of linear expansion, which in this case is aluminum.

This phenomenon is utilized in devices such as bimetallic thermostats or thermometers, where the bending of the strip is used to indicate temperature changes.

Answer 2

We can base this on the equation of thermal expansion.

ΔL = L₀αΔT
where
ΔL is the expansion of length upon heating
L₀ is the initial length
α is the coefficient of linear expansion
ΔT is the temperature difference

So, if α for Aluminum is greater than α for Copper, then after heating, aluminum would be longer than copper.