A force of pounds is required to hold a spring stretched 0.4 feet beyond its natural length. How much work (i

1. A force of pounds is required to hold a spring stretched 0.4 feet beyond its natural length. How much work (in foot-pounds) is done in stretching the spring from its natural length to 1 feet beyond its natural length?

2. A chain 22 feet long whose weight is 61 pounds is hanging over the edge of a tall building and does not touch the ground. How much work is required to lift the entire chain to the top of the building?

1. A force of x pounds is required to hold a spring stretched 0.4 feet beyond its natural length. How much work (in foot-pounds) is done in stretching the spring from its natural length to 1 feet beyond its natural length?

Force = k *distance stretched
x = k * 0.4
k = x ÷ 0.4

Work = average force * distance stretched
Average force = ½ * (Initial force + Final force)
Initial force = 0 lb.
Final force = k * 1= (x ÷ 0.4) * 1 = (x ÷ 0.4)

Work = ½ * (x ÷ 0.4) lb * 1 ft


2. A chain 22 feet long whose weight is 61 pounds is hanging over the edge of a tall building and does not touch the ground. How much work is required to lift the entire chain to the top of the building?

AS you move the chain upward, the weight of the chain hanging over the edge of the tall building decreases from 61 pounds to 0 pounds.
Work = average force * distance moved
Work = average force * distance moved
Average force = ½ * (Initial force + Final force)
Initial force = 61 N
Final force = 0 N
Work = ½ * 61 * 22