# Homework Help: How to make equations out of this data(spring moving 2D)

1. Mar 14, 2009

### transgalactic

a disk with radius R and mass M is sticked on axle that goes threw
the center of the table.
between the disk and the table there is no friction.
on the big disk there is a smaller disk without mass with radius r
and a weight less rope is wrapped around it.
this rope is connected to a spring with elastic constant K .
the springs other end is connected to a wall.

we assume that the system is at equilibrium .
and we throw a mass m on the big disk with velocity $$V_0$$
and it hits her in point A on angle $$\alpha$$
the collision is absolutely elastic and mass m sticks to the disk.

because of the collision the system start to do harmonic movement.
and particularly angle$$\Theta$$ describes the position of point A of the disk.
point A also moves harmonically $$\Theta=\Theta_0\cos(\omega t+\beta )$$

calculate the amplitude of $$\Theta_0$$
??

this is a question from hell i get the impression that the spring is moving from right to left and from top to bottom.

usually i put forces and from them i calculate what i need .
but here
i dont know from what place to start
from what equations to start and how to proceed ??

if i start from the collision?
with respect to what point do i need to calculate angular momentum(rmv) equations??

i cant understand why in the solution they say that the amplitude of the spring A is
A=R$$\Theta_0$$
??

Last edited: Mar 14, 2009