A rapid, sudden pull. Also, the first derivative of acceleration; hence the third derivative of position. Its algebraic symbol is j. Sometimes called jolt.

Also, a jerk can be a person who jerks other people around (metaphorically) -- one who casually behaves in a rude or unpleasant manner.

One important type of jerk which this node has missed so far:

Recently got to visit Jamaica for the first time, and it was quite a trip. In the drug free sense of the word, though. Really. I promise!

Anyway, when my brother brought me to the Kingston Jerk Center, I first thought he was trying and failing to be funny. But, as you should know, Jerk is the Jamaican style of barbeque. It's flavored strongly with allspice berries, and cooked for hours in a pit filled with pimento tree wood. I only had jerked chicken, but pretty much anything can be jerked.

While jerk flavoring tends to be spicy, it is also safe for the overly sensitive people out there. My girlfriend can't stand the heat of Taco Bell mild hot sauce, but she likes jerk chicken. But the heat can also be increased to dangerous levels if that's what you like.

In physics terms...

Jerk is basically the rate of acceleration.

• When jerk is at a constant value, the acceleration is changing at a constant rate, thus the velocity is changing quadratically.
• When jerk is increasing at a constant rate, acceleration is increasing quadratically. The jerk also decreases at a constant rate as the acceleration decreases quadratically.
• When jerk increases quadratically, the acceleration increases cubically, making the velocity increase to the fourth degree. The same situation occurs when they are all decreasing.
• When jerk exponentially decays, the acceleration decreases at a constant rate, which means the velocity would be decreasing quadratically.

Jerk is what is mainly describes as a sudden change in acceleration, such that if the acceleration is at a constant value most of the time, and it increases the value within a short period of time and goes back to constant, the jerk would be a little bump if this was shown on a graph. This is what causes motion sickness due to the unexpectancy of change in acceleration.

In math terms...
Jerk is the derivative of acceleration, as acceleration is the derivative of velocity, etc. This makes jerk the second derivative of velocity.

If the function of velocity is:
(Let t = time in seconds, and f(t) be the distance, in meters.)

v = f(t) = 8t2
...where the domain of t is [0, )

a = f'(t) = 16t
j = f''(t) = 16
jerk is constantly at 16 when the velocity is at 8t2.

All in all, jerk, in this context, is a form of movement, not to get mixed up with a passenger who would furtively shift the car to reverse in the middle of heavy traffic, or someone who would grind sleeping pills into your cereal on the morning of SAT's. That would be of slightly different context.

Jerk (?), v. t. [Corrupted from Peruv. charqui dried beef.]

To cut into long slices or strips and dry in the sun; as, jerk beef. See Charqui.

Jerk, v. t. [imp. & p. p. Jerked (?); p. pr. & vb. n. Jerking.] [Akin to yerk, and perh. also to yard a measure.]

1.

To beat; to strike.

[Obs.]

Florio.

2.

To give a quick and suddenly arrested thrust, push, pull, or twist, to; to yerk; as, to jerk one with the elbow; to jerk a coat off.

3.

To throw with a quick and suddenly arrested motion of the hand; as, to jerk a stone.

Jerk, v. i.

1.

To make a sudden motion; to move with a start, or by starts.

Milton.

2.

To flout with contempt.

Jerk, n.

1.

A short, sudden pull, thrust, push, twitch, jolt, shake, or similar motion.

His jade gave him a jerk. B. Jonson.

2.

A sudden start or spring.

Lobsters . . . swim backwards by jerks or springs. Grew.