How Does Spring Constant Affect Work Done on a Stretched Spring?

[grouchy]

Homework Statement

A spring with a spring constant f 15 N/cm has a cage attached to one end.
a) How much work does the spring force do on the cage when the spring is stretched from its relaxed length by 7.6 mm?
b) How much additional work is done by the spring force when the spring is stretched by additional 7.6 mm?


I converted the 7.6 mm to .76 cm but I aint sure on the question for this. Is it W - 1/s x 15 x .76 ?

 

[pinkyjoshi65]

use W=0.5KX^2 to find the work done..