# Homework Help: Problem with angular velocity

1. Nov 13, 2015

### GiuseppeR7

• Moved from a technical forum, so homework template missing
I have the "robotic arm" shown in figure...the angular speeds w1, theta, w3 are given...they are asking me to find the total angular velocity of the disk. Can anyone explain me (conceptually) 1) what do we mean by total angular velocity of the disk and 2) how to find it...i have not understood anything! http://postimg.org/image/vexp5fh79/

2. Nov 13, 2015

### jbriggs444

At any given instant, the motion of a rigid object can be described as a rotation (direction and rate) combined with a translation (direction and rate). Over time the rotation may change rate or direction or both. The instantaneous axis of rotation may or may not go through a line of symmetry of the object. The rotation may or may not be stable in the absence of external forces.

As I read the problem, you are being asked to find the angular velocity (axis and rate) of the disk at an instant when the configuration is as illustrated. This looks at least homework-like and should have been posted in one of the homework sub-forums.