Rotational Kinematics (String attached to disk)

[mattj150]

Homework Statement

Determine the relationship between the angular
acceleration of the flywheel, the downward acceleration of the block, and the radius of
the ring.

Known data:
Mass Ring: 1.420 kg
Radius Ring (Inside, then Outside): 5.10 cm, 6.325 cm
Mass Disk: 1.455 kg
Radius Disk: 11.45 cm
Mass Shaft: Negligable
Radius Shaft: 0.6 cm

Homework Equations

ω=ω0 + αt
f=ma

The Attempt at a Solution

I'm really lost on this, i assume that i need to calculate the tension the block places on the string (F=MA)? Could anyone give me a hint on how to get started on this.

 

[Simon Bridge]

Welcome to PF;
Your wish is my command:
hint: draw free-body diagrams.

Though you could use conservation of energy and assume acceleration is constant.

 

[mattj150]

I understand how to do the FBD for the hanging mass. The forces acting on it are simply Fg and Ft. How would i do a FBD for the spinning mass? Would i pick a point on the outer edge to do it for?

 

[Simon Bridge]

The tension force acts at a particular location on the flywheel - creating a torque. $\tau=I\alpha$