A rubber cord of cross-sectional area 2cm2 has a length of 1m. When a tensile force of 10N is applied the length of the cord increases by 1cm. What is the youngs modulus of rubber ?
Correct answer: B. 5 x 10^6 Nm-2
- A. 2 x 10^8 Nm-2
- B. 5 x 10^6 Nm-2
- C. 0.5 x 10^-6 Nm-2
- D. 0.2 x 10^-6Nm-2
Explanation
Young's modulus is Y = FL/(AΔL). Converting 2 cm^2 to 2 x 10^-4 m^2, Y = (10 N)(1 m)/[(2 x 10^-4 m^2)(0.01 m)] = 5 x 10^6 N m^-2. The likely mistake is option a, which results from mishandling the area or the 1 cm extension.
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