‫Welcome back.
‫In this video, we will very quickly talk about the direction of a rotation vector when you have some
‫kind of random object and it has some kind of velocity in this direction, well, then you intuitively
‫know that this object is going to move in this direction.
‫However, what would be the direction of rotation?
‫Let's say that here you have random object rotating and it is rotating like shown here in red and here
‫in blue.
‫This is the rotation plane.
‫So this red is drawn on this blue plane.
‫In the direction of this rotation is this Green Arrow, which is perpendicular to the rotation plane.
‫In other words, this green vector is perpendicular to this blue plane.
‫So here you can see this perpendicular sign.
‫And so let's say that this object is rotating at, let's say, Alpha Dot or the Alpha DETI.
‫Let's see, it's rotating at 10 radians per second.
‫So this is angular velocity and angle of velocity, a vector, which means that it also has to have
‫a direction.
‫And so if this object rotates 10 radians per second on this blue rotation plane or like you see it in
‫red, then the direction of the angular velocity vector would be perpendicular to this rotation plane.
‫So it would be this Green Arrow.
‫So this would be your angular velocity vector.
‫And then the length of this arrow would be the magnitude of the velocity vector, which would be 10
‫radians per second.
‫And if instead of angular velocity, you had angular acceleration, let's say five radians per second
‫squared, then if this angular acceleration happens on this blue rotation plane, then again, the direction
‫of this vector would be perpendicular to this plane, either in this direction or in the opposite direction,
‫depending on the right hand rule.
‫Also, the same would apply to an angular position vector.
‫Let's see if you just have alpha equals, let's see, two radians.
‫So the object has rotated to radians, but then you ask in which direction.
‫And so this arrow would give you the direction, which means the rotation happens around this arrow.
‫So the object rotated to radians around this arrow.
‫So you have to grab this arrow with your right hand and then you see where the sun points and then you
‫know the direction of the vector and the same thing.
‫You can have a talk or a moment.
‫Remember, talking a moment are actually the same thing.
‫Let's say equal seven Newton meters.
‫Again, a moment creates rotation.
‫So it is also related to rotation.
‫So, again, if you have a moment, whose direction is this Green Arrow, then you know that this object
‫wants to start rotating like shown here in red.
‫So the direction of a rotation is perpendicular to the rotation plain.
‫And if there is a change in the rotation direction, then this would be the change of it and this would
‫be your new rotation vector.
‫That means that also the rotation plane would adjust itself so that it would now be perpendicular to
‫this vector.
‫So I hope it's clear now.
‫Thank you very much and see you in the next video.