A spring has a natural length of 2 ft, and a force of a 15 lb is required to hold it compressed at a length of 18 in. How much work is done in stretching this spring from its natural length to a length of 3 ft?

Working:

x=compression=2-1.5=0.5 ft

F=kx

15=k*0.5

k=30 lb/ft

=

=

= 15*1

= 15 lb-ft

Edit:Never mind; I solved it myself.