A compressive force, F is applied at the two ends of a long thin steel rod

PHYSICS · Single correct · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A compressive force, F is applied at the two ends of a long thin steel rod. It is heated, simultaneously, such that its temperature increases by

\Delta T

. The net change in its length is zero. Let l be the length of the rod, A its area of cross-section, Y its Young's modulus, and

\alpha

its coefficient of linear expansion. Then, F is equal to: (1)

l^2 Y \alpha \Delta T

(2)

l A Y \alpha \Delta T

(3)

A Y \alpha \Delta T

(4)

\frac{A Y}{\alpha \Delta T}