A Force of 10 Pounds Compresses a 21-Inch Spring 8

Multiple Choice

A force of 10 pounds compresses a 21-inch spring 8 inches. How much work is done in compressing the spring from a length of 15 inches to a length of 13 inches?

A) 22.5 ft-lb
B) 19.5 ft-lb
C) 17.5 ft-lb
D) 12.5 ft-lb
E) 27.5 ft-lb