Physics - Elasticity Question with Solution | TestHub

Young's modulus (Y) is defined as stress divided by strain.$$Y=\frac{\text{Stress}}{\text{Strain}}=\frac{F/A}{\Delta L/L}$$ So, elongation $\Delta L=\frac{FL}{AY}$. Given $F=10\text{ N}$, $L=2\text{ m}$, $A=1{\text{ mm}}^2=1\times 10^{-6}{\text{ m}}^2$, $Y=1\times 10^{11}{\text{ N/m}}^2$.$$\Delta L=\frac{10\text{ N}\times 2\text{ m}}{(1\times 10^{-6}{\text{ m}}^2)\times (1\times 10^{11}{\text{ N/m}}^2)}=\frac{20}{10^5}=20\times 10^{-5}\text{ m}=200\times 10^{-6}\text{ m}$$

Since $1\text{ mum}=10^{-6}\text{ m}$, the elongation is $200\text{ mum}$. The integer answer is 200.