A copper cube with edges of 12 cm is put in a tank where the pressure is raised by 3.5 × 10⁷ Pa…

Step 1. Fraction. $\dfrac{3.5 \times 10^{7}\ \text{Pa}}{1.4 \times 10^{11}\ \text{Pa}} = 2.5 \times 10^{-4}$.

Step 2. Volume. $V = 1728\ \text{cm}^3$, so $\Delta V = 0.432\ \text{cm}^3$.

Step 3. Edge. $\Delta a = 0.12\ \text{m} \times \dfrac{2.5 \times 10^{-4}}{3} = 1.0 \times 10^{-5}\ \text{m}$.