A spring has a natural length of 28 cm. If a 27-N force is required to keep it stretched to a length of 32 cm, how much work W is required to stretch it from 28 cm to 30 cm? (Round your answer to two decimal places.) W = 13.5 Incorrect: Your answer is incorrect. J

0.14 J

Explanation:

Use the force to calculate the spring constant.

F = k Δx

27 N = k (0.32 m - 0.28 m)

k = 675 N/m

Work is the change in energy:

W = PE

W = ½ k (Δx) ²

W = ½ (675 N/m) (0.30 m - 0.28 m) ²

W = 0.135 Nm

W = 0.135 J

Rounding to two decimal places, W = 0.14 J.

Your answer was correct, but it was in units of Ncm, and you needed to answer in units of J.