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Does a rigid rod store any energy?

  1. Mar 8, 2015 #1
    I presume that a rod can be modelled as a spring with spring constant k and compression x.

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

    Is that correct?
  2. jcsd
  3. Mar 8, 2015 #2
    You answered your own question.

  4. Mar 8, 2015 #3


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    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.
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