# solving a physic problem using sage

Hi, I'm new in this community.

I want to solve a physic problem which requires differential equation system solutions.

I don't know if my equations are correctly set. Any suggestion is good. My problem is described by this image: http://img805.imageshack.us/img805/70...

I have two masses (1/3m the first, 2/3m the second) linked with a rope. The rope is free to slide around a nail (the big black point in the image). The image shows the starting condition: a man keeps the first mass stopped and so the rope is kept stretched by the second mass.

I search three functions describing the kinematics of two masses after the man will leave the fist mass: vertical movement of mass A y(t), vertical movement of mass B j(t), and horizontal movement of mass B x(t).

My Cartesian reference system is x-y system in the image.

I have to solve the following equations:

- $-\frac{2}{3}mg+T=\frac{2}{3}m \frac{d^2y}{dt^2}$
- $-\frac{1}{3}mg+S_y=\frac{1}{3}m\frac{d^2j}{dt^2}$
- $S_x=\frac{1}{3}m\frac{d^2x}{dt^2}$
- $|T|=\sqrt{S_x^2+S_y^2}$
- $|y(t)|=\sqrt{x(t)^2+j(t)^2}$

From the forth and the fifth equations I obtain two equations, so I have 5 equations in 5 unknowns. They are:

1) T force sustaining the second mass

2) Sx x-component of force sustaining the first mass

3) Sy y-component of force sustaining the first mass

4) y(t) position of the second mass

5) x(t) x-position of the first mass

6) j(t) y-position of the first mass

I hope my explanation is clear.

How can I obtain my solutions using Sage?

Thank you very much!!

No one can help me???

Is my problem too difficult to set on Sage that no one could help me?

Help!!Help!!Help!!

After years, someone else could suggest a solution with Sage?