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I was researching rays recently, and found that they had the same notation as vectors (namely an arrow pointing in one direction). My question is why does these two clearly different concepts have the same notation?

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    $\begingroup$ Vector is finite, ray is infinite. $\endgroup$
    – xrfxlp
    Commented Jun 20, 2019 at 16:11
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    $\begingroup$ There are more concepts out there than there are typographical symbols. $\endgroup$
    – saulspatz
    Commented Jun 20, 2019 at 16:12
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    $\begingroup$ They're clearly different concepts, but at the same time very closely related. $\endgroup$
    – John
    Commented Jun 20, 2019 at 16:22

1 Answer 1

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Vector and ray are symbolized the same way: a line segment with an arrow on one end but they are very different things.

A vector has a direction and a magnitude (for example, 5 km south-east).

Vector be like this:

enter image description here

A ray has just a direction and a starting point, and it has infinite length. A ray would be like starting where you are now in the direction south-east. One end ends in a point, and the other is a line.

Ray is like this:

enter image description here

When an arrow represents a vector, it is understood that the magnitude of the vector is finite, and that the length of the arrow is approximately proportional to the magnitude of the vector.

When an arrow represents a ray, it is understood that the ray continues without end in the direction indicated by the arrowhead, and that the length of the arrow has no significance.

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