Why does the P come before the Q in relative displacement vector notation?

In summary, the conversation discusses the relationships between three points, O, P, and Q. The equations OP = rP and OQ = rQ are mentioned, and there is confusion about why QP is written as PrQ instead of QrP. The summary explains that this notation is used because QP is equal to the difference between the coordinates of OP and OQ. The speaker also expresses a desire to understand this concept better.
  • #1
Ultrimo
1
0
We have 3 points. O, P, Q.

OP = rP
OQ = rQ
but why is QP PrQ rather than QrP?

I'm just starting M4 and I really like to understand everything. This doesn't make any sense to me and I can't find out online. I'm sure there's a logical reason for it to be like that. Is it because you go along to rQ and then along to P?
 
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  • #2
Ultrimo said:
We have 3 points. O, P, Q.

OP = rP
OQ = rQ
but why is QP PrQ rather than QrP?
Your notation doesn't make any sense to me.

QP = OP - OQ

If the coordinate form of OP is <p1, p2>, and the coordinate form of OQ is <q1, q2>, then QP = <p1 - q1, p2 - q2>.
Ultrimo said:
I'm just starting M4 and I really like to understand everything. This doesn't make any sense to me and I can't find out online. I'm sure there's a logical reason for it to be like that. Is it because you go along to rQ and then along to P?
 

1. Why is the P before the Q in relative displacement vector notation?

In relative displacement vector notation, the letter P represents the initial point or starting point of the displacement, while the letter Q represents the final point or end point of the displacement. Therefore, it makes sense for P to come before Q as the starting point must be identified before the end point in order to determine the direction and magnitude of the displacement.

2. Is there a specific reason for using the letters P and Q in relative displacement vector notation?

The letters P and Q are commonly used in mathematics and physics as variables to represent points or positions. In relative displacement vector notation, P and Q are used to represent the initial and final points respectively, and are chosen to maintain consistency with other mathematical notations.

3. Can the letters P and Q be interchanged in relative displacement vector notation?

No, the letters P and Q cannot be interchanged in relative displacement vector notation. As mentioned before, P represents the starting point and Q represents the end point, and switching them would result in a different direction and magnitude of the displacement.

4. Is relative displacement vector notation the only way to represent displacements?

No, there are other ways to represent displacements such as using Cartesian coordinates or polar coordinates. However, relative displacement vector notation is commonly used in physics and engineering as it is a convenient way to represent both the direction and magnitude of a displacement.

5. How does the placement of P and Q affect the direction of the displacement vector?

The placement of P and Q in relative displacement vector notation determines the direction of the displacement vector. If P is placed before Q, then the displacement vector points towards the final point Q. However, if Q is placed before P, then the displacement vector points towards the initial point P.

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