# Jounce: Wikis

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# Encyclopedia

In physics, jounce or snap is the fourth derivative of the position vector with respect to time, with the first, second, and third derivatives being velocity, acceleration, and jerk, respectively; in other words, the jounce is the rate of change of the jerk with respect to time.

$\vec s=\frac {d \vec j} {dt}=\frac {d^2 \vec a} {dt^2}=\frac {d^3 \vec v} {dt^3}=\frac {d^4 \vec r} {dt^4}$

Currently, there are no well-accepted designations for the derivatives of jounce. 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.

## References

1. ^ Visser, Matt (2004-07-24). "Jerk, Snap, and the Cosmological Equation of State". Classical and Quantum Gravity 21 (11): 2603–2616. doi:10.1088/0264-9381/21/11/006. ISSN: 0264-9381. Retrieved 2007-08-24.
2. ^ Gragert, Stephanie (November 1998). "What is the term used for the third derivative of position?". Usenet Physics and Relativity FAQ. Math Dept., University of California, Riverside. Retrieved 2008-03-12.