JEE Main 2014 · 6 Apr · Shift 1 · Physics Q8

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PhysicsSingle correct+4 / -1Question 8 of 90

The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is :

(For steel Young's modulus is $2\times10^{11}$ N m $^{-2}$ and coefficient of thermal expansion is $1.1\times10^{-5}$ K $^{-1}$ )

2.2\times10^8

2.2\times10^9

2.2\times10^7

2.2\times10^6

Answer and worked solution

Official answer: A

The applied stress must cancel the thermal strain $\alpha\Delta T$ :
$\sigma=Y\alpha\Delta T=2\times10^{11}\times1.1\times10^{-5}\times100=2.2\times10^8\text{ Pa}.$
(The length does not matter.)

Topics:Thermal stress

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JEE Main 2014 · 6 Apr · Shift 1, Physics question 8