Quote:
|
So, what do we do with k? Well, if we increase k, we get a shorter draw but the same amount of force. If we decrease k, we get a longer draw, but the same amount of force. In the end, the force (remember F=ma?) remains the same (as does mass and acceleration). The only thing we change is the draw.
|
You are forgetting about pre-load.
1) Assuming that both the strong spring and the weak spring have the same pre-load force, then the weak spring will be pulled back further
and have more stored energy.
or
2) Assuming you increase the pre-load on the weaker spring just enough that the motor stalls at the same position as the strong spring, you will also have
more stored energy in the weaker spring.
If you have trouble believing this, make a simple graph of force versus distance for each case and look at the area under the curve.
~