First of all--it's Prime 6, not 3. (Since I'm using 4.0 Express, I could tell.)
Second--Potential energy can't be negative (I understand why you're showing it that way, but . . .)
In the absence of dissipation, and if the pendulum is rigid, total energy will be constant. So if we make kH = 0, we should get a graph like this:
I have put a marker here on the total energy level. Now, if we let the pendulum be a spring:
The calculated potential energy is WAY TOO HIGH. The kinetic has increased too, but there's only so much energy to start, and both calculations started at the same condition.
Attached is the (somewhat messy) Prime 4.0 Express sheet.
Sorry, a potential eneggy can be negativ - see please the picture (a hard link!).
May be the problem in the function for le.
You're right, of course; the potential energy is defined relative to an arbitrary zero point.
There are two potential energies to be tracked:
And two kinetic energies:
And, if I did it right (within calculation accuracies) they now track:
We have a physical point (mass without size) and a weightless non-bendable spoke that compresses or stretches according to Hooke's law.
There are three energies:
- kinetic energy of a physical point
- potential energy of a physical point
- energy of compression or stretching of the spoke
The sum of these three energies must be constant if we do not take into account friction (k_f = 0), or it must decrease (k_f > 0).
a weightless non-bendable spoke that compresses or stretches according to Hooke's law. This is a spring! And the "physical point" is moving radially as the non-bendable spoke compresses or stretches. So there is a fourth energy, the kinetic energy of that radial motion.
I would like see the plot - the summ energies as function od time at k_f=0 it is
Can you not execute my sheet? It's easy to change parameters, it's your table!
Sorry Valery,
This was your project:
I'm just trying to help. Both of us are missing something, where is your input? 🙂
