degree
Azimuth
Azimuth
most common military method of expressing direction
The most common military method of expressing direction is using the clock system. In this system, the direction an object or target is located is described relative to the position of an individual, with 12 o'clock being directly in front, 6 o'clock behind, and so on.
Dotted decimal notation
The most common thing you would measure mass in would be grams and kilograms
Grams
A protractor
A planispharic disc
That is the most common direction in which tornadoes travel, but they can move in any direction.
A spectrometer is used to measure properties of light. The most common usage is as an instrument attached to a telescope for astronomers to measure the chemical elements in a star.
Any measure of length will do, but the most common would be feet or meters.