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.