7.4 Unit vector notation by Benjamin Crowell, Light and Matter licensed under the Creative Commons Attribution-ShareAlike license.
When we want to specify a vector by its components, it can be cumbersome to have to write the algebra symbol for each component:
Δx=290km, Δy=230km
A more compact notation is to write
Δr=(290km)ˆx+(230km)ˆy,
where the vectors ˆx, ˆy, and ˆz, called the unit vectors, are defined as the vectors that have magnitude equal to 1 and directions lying along the x, y, and z axes. In speech, they are referred to as “x-hat” and so on.
A slightly different, and harder to remember, version of this notation is unfortunately more prevalent. In this version, the unit vectors are called ˆi, ˆj, and ˆk:
Δr=(290km)ˆi+(230km)ˆj.
7.4 Unit vector notation by Benjamin Crowell, Light and Matter licensed under the Creative Commons Attribution-ShareAlike license.
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