Pendulum project update

[Phil Firsenbaum]

So, I've done a little reading (Physics Made Simple, etc,) and most 
recently consulted with a physics professor who happens to be in the 
family. As a result, I'm fairly (if not completely) convinced that 
creating a realistic pendulum is well beyond what 5th graders could do. 
I'm not even sure if I'll ever be able to complete the project myself.
I have learned a lot about pendulums, gravity, etc.
I realize now that my pendulum does not reflect reality because it 
moves at a steady rate through it's swing when, in fact, a pendulum 
accelerates in its downward motion and decelerates in its upward motion.
In order to simulate reality I need to be able to change the rate of 
acceleration of the heading of my pendulum. I now have a formula that 
would accomplish this, however, it includes a square root function. Is 
that possible in the etoy environment?