Answer:
36.3 lb-ft
Explanation:
F = force required to hold the spring stretched = 6 lb
x = stretch in the spring = 0.1 ft
k = spring constant
Using the equation
F = k x
6 = k (0.1)
k = 60 lb/ft
U = work done in stretching the spring
x' = 1.1 ft
Work done in stretching the spring is given as
U = (0.5) k x'²
U = (0.5) (60) (1.1)²
U = 36.3 lb-ft