In a test, a wire 1.5 m long and 0.60 mm across stretches 3.2 mm when a 7.0 kg mass hangs from it…

Step 1. $F = 68.6\ \text{N}$ and $A = \pi(0.30 \times 10^{-3}\ \text{m})^2 = 2.83 \times 10^{-7}\ \text{m}^2$.

Step 2. $Y = \dfrac{68.6\ \text{N} \times 1.5\ \text{m}}{2.83 \times 10^{-7}\ \text{m}^2 \times 3.2 \times 10^{-3}\ \text{m}} = 1.14 \times 10^{11}\ \text{Pa}$.