A metal rod measures $100\text{ cm}$ at $20^\circ\text{C}$. When heated to $80^\circ\text{C}$, its length…
A metal rod measures $100\text{ cm}$ at $20^\circ\text{C}$. When heated to $80^\circ\text{C}$, its length increases to $100.2\text{ cm}$. What will its length be when cooled back to $20^\circ\text{C}$?
$100.2\text{ cm}$
$100\text{ cm}$
$99.8\text{ cm}$
$100.4\text{ cm}$
Solution
Thermal expansion contracts back reversibly when cooled; returning to the original temperature restores the original length of $100\text{ cm}$.