A steel bar of 2 m length is fixed at both ends at 20°C. The coefficient of thermal expansion is 11 x 10-6/°C and the modulus of the elasticity is 2 x 106 kg/cm2. If the temperature is changed to 18°C, then the bar will be experience a stress of
A. 22 kg/cm2 (tensile) B. 22 kg/cm2 (compressive) C. 44 kg/cm2 (compressive) D. 44 kg/cm2 (tensile)
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ΔL = L * α * ΔT = 2 * 11 * 10^-6 * -2 = - L * 22 * 10^-6 meters
Y = Stress / Strain => Stress = Strain * Y
Stress = Y * ΔL / L = - 2 * 10^6 * 10^4 * 22 * 10^-6 = - 44 * 10^4 N
= - 440 Kilo Newtons / meter²
= - 44 N/cm²
Compressive as Stress is -ve.
ANswer is C
Y = Stress / Strain => Stress = Strain * Y
Stress = Y * ΔL / L = - 2 * 10^6 * 10^4 * 22 * 10^-6 = - 44 * 10^4 N
= - 440 Kilo Newtons / meter²
= - 44 N/cm²
Compressive as Stress is -ve.
ANswer is C
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