I had a friend and colleague ask me today about why the angular velocity and angular acceleration vectors point in directions given by the right-hand-rule, as highlighted here... When I read my response, I realized that my answer wasn't much better than that given in the link... I thought about it some more and started thinking that it probably related to:

and since the cross product of r and F is perpendicular to both r and F, with the positive direction given by RHR, the angular acceleration (and similarly angular velocity) vector must be consistent.

Still not a very pleasing or clear explanation. So, why not turn to the experts? If someone were to ask you, how would you explain the direction of the angular velocity and angular acceleration vectors in a manner that was as clear and straightforward as possible?

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## FizziksGuy

Hi All,

I had a friend and colleague ask me today about why the angular velocity and angular acceleration vectors point in directions given by the right-hand-rule, as highlighted here... When I read my response, I realized that my answer wasn't much better than that given in the link... I thought about it some more and started thinking that it probably related to:

and since the cross product of r and F is perpendicular to both r and F, with the positive direction given by RHR, the angular acceleration (and similarly angular velocity) vector must be consistent.

Still not a very pleasing or clear explanation. So, why not turn to the experts? If someone were to ask you, how would you explain the direction of the angular velocity and angular acceleration vectors in a manner that was as clear and straightforward as possible?

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