Steel wire of length ‘L’ at 40°C is suspended from the ceiling and then a mass ‘m’ is hung from its free end. The wire is cooled down from 40°C to 30°C to regain its original length ‘L’. The coeffici…

Question

Steel wire of length ‘L’ at 40°C is suspended from the ceiling and then a mass ‘m’ is hung from its free end. The wire is cooled down from 40°C to 30°C to regain its original length ‘L’. The coefficient of linear thermal expansion of the steel is 10^–5 /°C, Young’s modulus of steel is 10^11 N/m^2 and radius of the wire is 1 mm. Assume that L >> diameter of the wire. Then the value of ‘m’ in kg is nearly.

Accepted Answer

Correct answer: 3. (3) We know that E= F/A L/L ⇒ LL= F AE … (i ) Also LL= T … ( ii ) F AE= T ⇒ mg= ( T ) AE ⇒m= Tg AE= 10^-5 10 10^-6 10^1110= ≈3

Solution

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