A spring has k = 350 N/m. How much work does it take to stretch it from 0 cm to 8.0 cm; from 8.0 cm…

Step 1. (a) $\tfrac12 \times 350\ \text{N/m} \times (0.080\ \text{m})^2 = 1.12\ \text{J}$.

Step 2. (b) $\tfrac12 \times 350\ \text{N/m} \times ((0.16\ \text{m})^2 - (0.080\ \text{m})^2) = 175\ \text{N/m} \times 0.0192\ \text{m}^2 = 3.36\ \text{J}$.