Error solving 5 diff. equations with NDSolve

Questions
, ,
1

Hello, I am a student from South Korea, and I have used mathematica for solving IYPT #8. Euler’s Pendulum. I made 5 equations with using Newton Mechanics, and there are 5 functions that I want. I used NDSolve to draw graphs of them, but the error occurs. I don’t have any idea with these errors. Can you help me please?

031223_iypt.nb (98.4 KB)

2

There is an typo: a Sqrt( argument) expression with ()-brakets.
Replace by Sqrt[argument]

3

The unknown function psi[t] does not appear as derivative. Your equations are not true differential equations. You should also use the square braces in

r = Sqrt[(rx)^2 + (ry)^2 + (rz)^2]