Chapter 13, Problem 90A

To determine

The parts that are made of steel or aluminum.

Answer to Problem 90A

Part experienced greater reduction in length is made up of aluminum and part with lower reduction in length is made up of steel.

Explanation of Solution

Introduction:All materials experience a thermal expansion when the change in temperature is applied. Thermal expansion is a change in length, area, and volume of a material due to temperature change.

Formula of Linear thermal expansion is $\text{Δ}L\text{ = α }L\text{Δ}T$ .

Where,

$\Delta L$ is the change in length  $L_1$ ,

$\alpha$ is a coefficient of linear expansion,

$\Delta T$ is the change in temperature

$L$ is the length at a temperature $T$

If length and change in temperature are constant, change in length is directly proportional to the coefficient of expansion of a material.The coefficient of expansion of aluminum is more than steel.

If a change in temperature is negative than material experiences reduction in length and if it is positive material experiences increase in length.

Conclusion:Material with a higher coefficient of expansion experiences more change in length compared to a material with less coefficient of expansion. Therefore, parts made up of aluminum experience a greater reduction in length.