# Equilibrium of a spring and speed.

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1. Aug 27, 2015

### Alameen Damer

Let's say I have a mass attached to an oscillating spring on a friction less horizontal surface. Why is it that the speed of the mass is greatest at equilibrium? I would have thought it would be greatest just before reaching the amplitudes due to maximum kinetic energy?

2. Aug 27, 2015

### Vibhor

Because the restoring force accelerates the mass till it reaches the equilibrium position .

On the contrary , the speed decreases and becomes zero when the mass reaches the extreme point.

3. Aug 27, 2015

### Alameen Damer

I see so as it passes the equilibrium, does the net force begin acting opposite to the motion decreasing velocity?

4. Aug 27, 2015

### Vibhor

Right .

5. Aug 27, 2015

### Alameen Damer

Thank you

6. Aug 28, 2015

### Staff: Mentor

The restoring force always acts toward the equilibrium point. So, when the mass moves toward the equilibrium point, the force speeds it up; when it moves away, the force slows it down.