Question

A force of 18 lb is required to hold a spring stretched 2 in. beyond its natural length. How much work W W is done in stretching it from its natural length to 7 in. beyond its natural length

Answer 1

Explanation:

Average force is (19 + 0)/2 = 9 lb

2 inches = 1/6 ft

W = Fd = 9(1/6) = 1.5 ft•lb