# Will a spring constant always remain the same?

1. Apr 7, 2012

### Pharris7

1. The problem statement, all variables and given/known data
A Mass, M, is at rest on a frictionless surface, connected to an ideal horizontal spring that is unstretched. A person stretches the spring 30cm from equilibrium and holds it at this location by applying a 10N force. The spring is brought back to equilibrium and the mass connected in now 2M. If the spring constant is extended back 30 cm from equilibrium, what is the necessary force that must be applied by the person to hold the mass stationary there?

2. Relevant equations

Fs=kx

3. The attempt at a solution

Well if there is a force of 10N pulling to one side, then to keep the mass still, the same force must be applied in the opposite direction.

To me it seems like the change in mass doesn't matter.

Could someone confirm this for me,

thanks
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Apr 7, 2012

### Staff: Mentor

Correct; the mass doesn't matter in this case.