Question

Why angular velocity is perpendicular on the plane of rotating? I knew it's from cross product,but I am looking for physical meaning.

Answer 1

You can demonstrate that the angular velocity is perpendicular to the plane of rotation by looking at the incremental changes occurring in a rotational scenario. See the attachment for details

Answer 2

the vector is the axis of rotation, if that gives it a good physical meaning. in fact, if you are talking about, say, a spinning disc, the vector is drawn through the points on the disc that are not actually moving! i ie those on the axis of rotation.

we need a vector because ang vel has both magnitude (how fast it is spinning) and direction (of spin/orbit).

the direction, ie right had rule, is then just a matter of convention. means we get the signs right when were adding vels or momenta or playing with torques.....

hope this helps you.

Answer 3

@gleem fantastic picture.thanks

@IrishBoy123 I hope I have not only one medal :(