# Thread: Need urgent help understanding vector

1. ## Need urgent help understanding vector

in vector,

is unit normal same meaning as unit vector?

postion vector means a point on the line for example?

If finding: " unit vector in the direction of the moment " does it mean unit vector/unit normal of moment? since they are parallel?

If finding: " unit vector normal to plane P" does it mean unit/normal vector of plane P?

many thks...

2. Originally Posted by MilK
in vector,

is unit normal same meaning as unit vector?

The unit normal is the Normal Unit Vector, it's common symbol is:

It's a Unit Vector, but in terms of the Normal Vector. They're the same as in they're both unit vectors, but they're not the same because a Unit Normal can only refer to a normal vector while a Unit Vector can be in any direction.

3. The unit normal is the Normal Unit Vector ==same as

If finding: " unit vector normal to plane P" does it mean unit normal of plane P?

4. The way I interpret that statement, they mean the same thing.

Find the vector normal to the plane, and then find a unit normal.

5. "vector normal to the plane P" ======== > vector of P ?

thks

6. Here's a picture that shows normal vectors, and here's a website:

Normal Vectors

This should give you an idea as to what a normal vector is, if you aren't that far in mathematics, then use it for the concepts that are presented at the beginning of the page.

Position Vectors usually represent an objects' position in space compared to an inertial reference frame.

Here's a site:

Position Vectors

Now, describing Unit Vectors in the direction of the moment is a little harder to do. First, here's a note on the direction of the moment:

The direction of a moment specifies the axis of rotation associated with the rotational force, following the right hand screw convention.

Next, I will describe the right hand rule:

1
The right hand screw rule states that, if you grip your right hand around the axis with your thumb pointing in the positive direction along the axis, your fingers will point in the direction of positive rotation.

2
The right hand screw rule states that positive rotation about the X-axis is defined by moving from the Y-axis to the Z-axis.

You can do some searching on your own if you would like defined formulas. The Moment stuff is prominent in engineering and Statics.