Solve Stiffness Question: Work to Change Spring Length

[clutch12]

Homework Statement

A spring has a relaxed length of 6 cm and a stiffness of 150 N/m. How much work must you do to change its length from 8 cm to 12 cm?

Homework Equations

1/2Ks,f - 1/2Ks,i

The Attempt at a Solution

1/2 Ks,f^2 - 1/2 Ks,i ^2
1/2 (150)(0.06m)^2 - 1/2(150)(0.02)^2
=0.24 N/m

Am i right or is it supposed to be a negative value?

 

[Delphi51]

Looks good to me! Definitely positive.

 

[clutch12]

Alright thanks