Physics - Heat & Thermo Question with Solution | TestHub

Rod is fixed at both ends, so the thermal compressive force $F$ is the same at every cross-section (internal restoring force).

(A) says force is maximum at mid-section: false, $F$ is uniform. So (A) is incorrect.

Stress:

$$\sigma =F/A$$

Left end has the smallest area, so $\sigma$ is maximum there: (B) correct.

Right end has the largest area, so $\sigma$ is minimum there: (D) correct.

Total length is fixed but each part expands/compresses differently, so strain exists: (C) incorrect.

Incorrect statements: A, C.