# Angular velocity/acceleration problem

Suppose disc A and B are spinning against each other without slipping or translating. What can be said about the motion of disc A in terms of B? (select all that apply; if none apply, leave the boxes blank)
Disk A has a diameter of 3D while disk B has a diameter of D

a. Angular velocity magnitude of A will be 3 times greater than B

b. Angular velocity magnitude of A will be equal to B

c. Angular velocity magnitude of B will be 3 times greater than A

d. Angular acceleration magnitude of A will be 3 times greater than B

e. Angular acceleration magnitude of A will be equal to B

f. Angular acceleration magnitude of B will be 3 times greater than A

L= Iw angular momentum = moment of inertia x angular velocity
t=Ia torque = moment of inertia x angular acceleration

Seeing from the question I think at the moment of contact, the velocity would be 0. But if we are looking at angular velocity as a whole, disk A should have 1/3 the speed of disk B. If that's the case then the angular acceleration diffeence would've also been 3 times between A and B. Can someone verify it?

## Answers and Replies

$$3w_A = w_B , \ \ \ 3\alpha_A = \alpha_B$$

there's nothing else