In physics, crackle is the fifth derivative of the position vector with respect to time, with the first, second, third, and fourth derivatives being velocity, acceleration, jerk, and jounce, respectively; in other words, crackle is the rate of change of the jounce with respect to time.
Currently, there are no wellaccepted designations for the derivatives of crackle. The fifth and sixth derivatives of position as a function of time are "sometimes somewhat facetiously" ^{[1]}^{[2]} referred to (in association with "Snap") as "Crackle" and "Pop", from the cereal characters; however, these terms have not gained widespread acceptance.

