How Displacement Is Determined:
Displacement magnitude is determined by mechanically measuring distance or by infers it with observations and mathematical computations. In the situation of a car or truck driving all along Route 52, the displacement is measured with an odometer which counts the number of wheel rotations and multiplies this by the circumference of the wheel. In a laboratory atmosphere, displacement magnitude can be measured with a meter stick, by triangulation, or by measure the time it takes for a ray of light to travel between two points given the constancy of the speed of light (c ≈ 2.99792 x 108 m/s).
The direction constituent of a displacement vector is determined by measuring one or more angles or coordinates associative to a reference axis. In the situation of a local area on the Earth's surface, direction can be found by identifying the azimuth, that is the angle clockwise associative to true north. This is the plan used by hikers and backpackers. In 3-dimensional space, direction angles are used. A reference axis, for illustration, a vector pointing toward Polaris, that is the North Star, is defined. Then two angles are identified in a coordinate system based on this axis. The most general system used by astronomers and space scientists includes angles known as celestial latitude and celestial longitude or, otherwise, right ascension and declination.