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
Delta-v (physics) Delta-v (physics) Delta comes as the 4th letter in the greek alphabets which is spell as 'D' in the english alphabets . In general physics, delta-"v" is simply a change in velocity. The Greek uppercase letter delta is the standard mathematical symbol to represent change in some quantity. Depending on the situation, delta-"v" can be either a spatial vector (Δv) or scalar (Δ"v"). In either case it is equal to the acceleration (vector or scalar) integrated over time: If acceleration is constant, the change in velocity can thus be expressed as: where: Change in velocity is useful in many cases,