Force done by the spring if a weight is attached

[dav1d]

Homework Statement

What is the force done by the spring if an object of mass m is attached.

Homework Equations

F=ma
F=-kx
Fg=mg

The Attempt at a Solution

Sum F = 0
mg-kx=0
mg-Fs=0
Fs=mg

Therefore the force done by the spring is mg? is the +/- right? for direction? Is the force right?

 

[Morphheus]

Properly think about it:

The mass is hanging from the spring. I assume that when it is observed, it can be considered at rest.
If it's at rest, there are only two forces acting on the mass: gravity and the spring force. Since the mass is at rest, all forces must cancel each other.
.
Since both forces are acting in opposite directions, they shouldn't have the same sign.

You stated that Sum F = 0. Therefore, Fs + Fg = 0

 

[dav1d]

Ok so then Fs=-Fg=-mg.
Just change the sign of my answer?

 

[Morphheus]

Yep.

 

[dav1d]

ok thank you very much! i thought the sign was a bit messed up.