JEE Main 2017 · 8 Apr · Shift 1 · Physics Q9

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PhysicsSingle correct+4 / -1Question 9 of 90

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 ΔT. 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 α its coefficient of linear expansion. Then, F is equal to :

l^2Y\alpha\Delta T

lAY\alpha\Delta T

AY\alpha\Delta T

\dfrac{AY}{\alpha\Delta T}

Answer and worked solution

Official answer: C

The thermal expansion $l\alpha\Delta T$ is cancelled by the compression $\dfrac{Fl}{AY}$ , so $F=AY\alpha\Delta T$ .

Topics:Thermal stress Temperature and thermal expansion

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JEE Main 2017 · 8 Apr · Shift 1, Physics question 9