Does a rigid rod store any energy?

[jcap]

I presume that a rod can be modeled as a spring with spring constant k and compression x.

The potential energy in a spring is given by:
<br /> E = \frac{1}{2}kx^2<br />
If the spring is in equilibrium with an applied force F then we have:
<br /> F = k x<br />
Thus the potential energy in the spring in terms of the force is:
<br /> E = \frac{1}{2}\frac{F^2}{k}<br />
Thus if we have a very stiff spring so that k\rightarrow\infty then the energy stored in the spring tends to zero for any force applied to the spring.

Is that correct?

 

[Chestermiller]

You answered your own question.

Chet

 

[CWatters]

Perhaps confirm it by looking at the work done by the applied force as it compresses the spring?

work = force * displacement

If the spring is very stiff the displacement is going to approach zero.