Question about the sign of angular velocity

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SUMMARY

The discussion centers on the interpretation of angular velocity and its sign in a physics problem. The correct formula for angular velocity is given as (2m*vi*d)/(((M,clay)+2m)*R^2). The user asserts that angular speed, defined as the magnitude of angular velocity, is always positive, while the teacher indicates that the angular velocity itself should be negative. The consensus is that angular speed is indeed positive, but angular velocity can be negative depending on the direction of rotation.

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Homework Statement


The problem is here: It is question #4,
http://faculty.mint.ua.edu/~pleclair/ph125/Exams/Ex3/ph125_s09_exam3.pdf

Homework Equations


See Below

The Attempt at a Solution


I have already gotten the answer and know it is correct:
(2m*vi*d)/(((M,clay)+2m)*R^2)
where m is the mass of the clay
My teacher says that the answer I have written above should have a negative sign in front of it. However, I thought angular speed was defined as the magnitude of angular velocity, meaning it is always positive. Who is correct here?
 
Last edited by a moderator:
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You are right, the angular speed was asked, and it is the magnitude of the angular velocity, positive.
The angular velocity itself is negative.

ehild
 

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