JEE Main2017PhysicsThermal Properties of MatterActual
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 Δ 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 α its coefficient of linear expansion. Then, F is equal to:
Options
- Al A Y α   Δ T
- BA Y α Δ T
- CAY α Δ T
- Dl 2 Y α Δ T
Correct answer
B. A Y α Δ T
Step-by-step solution
Net change in length = 0 Thermal expansion. Δ l = l α Δ t Y= F A Δ l l Δ l l = F AY Δ l = F l AY F l AY = l α Δ t F = AY α Δ t