# Jerk

Jerk is the change in the acceleration of an object. Mathematically, jerk is the derivative, or the rate of change of acceleration by time. Jerk is also called jolt (in British English), surge, or lurch. Jerk is a vector and there is no word for its scalar value.

The jerk is measured in metres per second cubed ($m/s^{3}$ ).

Yank can be thought as a force in terms of jerk. Force is mass times acceleration. Similarly, Yank is mass times jerk. It is also the derivative of the force. However, when an object is moving near the speed of light, a force is often written as the derivative of momentum. In this case, Yank is the rate of change of the derivative of momentum.

## Its use

Jerk is used in engineering, particularly in making roller coasters. Weak objects such as people can be damaged by high acceleration or high jerk. Also, jerk must be thought in the process of making any product. Sudden change in acceleration means very large jerk. Extent of exposure to jerk is often a good predictor of the rate of deterioration of tools while in normal use; it corresponds better to the appearance of metal fatigue among other modes of failure.