Thermal Properties of Matter

JEE Main level, numerical answer, medium

19 of 126

Question 19 of 126

A steel rod of length 1m1m and cross-sectional area 10−4m2{10}^{-4}{m}^{2} is heated from 0∘C0^{\circ}C to 200∘C200^{\circ}C without being allowed to extend or bend. The compressive tension produced in the rod is _____×104N\times {10}^{4}N. (Given Young's modulus of steel =2×1011Nm−2=2\times {10}^{11}N{m}^{-2}, coefficient of linear expansion =10−5K−1={10}^{-5}{K}^{-1} )

Show answer and solution

Answer: 4

The formula to calculate the Young's modulus of the material of the wire is given by
Y=FLA∆L...(1)Y=\dfrac{FL}{A∆L}...\left(1\right)
The increase in length of the wire due to increase in temperature is given by

∆L=Lα(T2−T1)...(2)∆L=L\alpha \left({T}_{2}-{T}_{1}\right)...\left(2\right)
Substitute the expression for the extension in length from equation (2) into equation (1) and simplify to obtain the required compressive tension.

Y=FLALα(T2−T1)⇒F=AαY(T2−T1)...(3)\begin{matrix}Y & = & \dfrac{FL}{AL\alpha \left({T}_{2}-{T}_{1}\right)} \\ & \Rightarrow & F=A\alpha Y\left({T}_{2}-{T}_{1}\right)...\left(3\right)\end{matrix}
Substitute the values of the known parameters into equation (3) to calculate the required compressive tension in the wire.

F=10−4m2×10−5K−1×2×1011Nm−2×(200∘C−0∘C)=4×104N\begin{matrix}F & = & {10}^{-4}{m}^{2}\times {10}^{-5}{K}^{-1}\times 2\times {10}^{11}{Nm}^{-2}\times \left(200^{\circ}C-0^{\circ}C\right) \\ & = & 4\times {10}^{4}N\end{matrix}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Thermal Properties of Matter (Thermal Expansion), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.