Question

A wire has a tensile strength of 70MPa, and breaks under 100N of force. What is the cross-sectional area of the wire just before breaking?

• A. $14.2\times {10}^{-6}{m}^2$
• B. $1.42\times {10}^{-6}{m}^2$
• C. $1.42\times {10}^{-3}{m}^2$
• D. $1.42\times {10}^{-2}{m}^2$

Answer 1

The correct option is B $1.42\times {10}^{-6}{m}^2$

The tensile strength = stress = force/area
Thus, $area=Force/Stress=100/(70\times {10}^6)=1.42\times {10}^{-6}{m}^2$
The correct option is option (b)