Symbols:K/Unit Vector

Unit Vector

$\mathbf k$

A unit vector, usually in the direction of the $z$-axis.

Hence it is usually aligned so as to be parallel to the vertical direction in a given frame of reference.

Sources

• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): k: 2 a. (conventionally printed in bold type)
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): Appendix: Table $7$: Common signs and symbols: vector
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): k (k)
• 2021: Richard Earl and James Nicholson: The Concise Oxford Dictionary of Mathematics (6th ed.) ... (previous) ... (next): k (k)