Solve the problem.
-A force of 1100 lb compresses a spring from its natural length of 20 in. to a length of 12 in. How much work is done in compressing it from 12 in. to 9 in.?
A) 620 in.-lb
B) 7800 in.-lb
C) 0.21 in.-lb
D) 3900 in.-lb

Question

Quizplus · Accepted Answer

First, we need to find the spring constant:
k = F/x = 1100/(20-12) = 137.5 lb/in

Then, we can find the work done in compressing the spring from 12 in. to 9 in.:
W = (1/2)k(x2^2 - x1^2) = (1/2)(137.5)(9^2 - 12^2) = 3900 in.-lb

Therefore, the answer is D.

Solve the Problem. -A Force of 1100 Lb Compresses a Spring from Its