A force of 3 pounds compresses a 15 inch spring a total of 3 inches. How much work (in ft-lbs) is done in compressing the spring 6 inches?

Answer 1

F = kx. The spring constant is F/x = 3/3 = 1. (F = force & x = distance spring compressed)

work = integral of kx from 0 to 6 inches which is kx^2/2 from 0 to 6. Which is 18 inch-lbs

that is 1.8 ft-lbs