Proper velocity Proper velocity In relativity, proper velocity, also known as celerity, is an alternative to velocity for measuring motion. Whereas velocity relative to an observer is distance per unit time where both distance and time are measured by the observer, proper velocity relative to an observer divides observer-measured distance by the time elapsed on the clocks of the traveling object. Proper velocity equals velocity at low speeds. Proper velocity at high speeds, moreover, retains many of the properties that velocity loses in relativity compared with Newtonian theory. For example, proper velocity equals momentum per unit mass at any speed, and therefore
Velocity Moments image formula_14, and similarly for formula_20. formula_21 introduces velocity into the equation as where formula_23 is the formula_18 coordinate of the centre of mass for the previous image, formula_25, and again similarly for formula_20. After the Cartesian velocity moment is calculated, it can be normalised by where formula_28 is the average area of the object, in pixels, and formula_29 is the number of images. Now the value is not affected by the number of images in the sequence or the size of the object. As Cartesian moments are non-orthogonal, so are Cartesian velocity moments, so different moments can be closely