The accelerometer is a device used to measure different kinds of acceleration, the rate of change of velocity. Its initial use was to validate the principles of Newtonian physics, including those of universal gravity.

The first accelerometer, originally known as the Atwood machine, was invented by the English physicist George Atwood (1746-1807) in 1783. There are two types of accelerometers. The instrument constructed by Atwood measures linear acceleration, such as that experienced by a falling object. A spring system is used to measure the accelerating force, which provides the acceleration via Newton's famous second law, force equals mass times acceleration (F=ma). Later accelerometers were designed to measure circular or twisting acceleration, such as that experienced by a weight spun at the end of a string. Here the acceleration depends on the radius of the circle of the spinning object.

There was little need for the Atwood accelerometer until the rise of the automobile industry. As demand increased, automakers found it necessary to make their vehicles safer and more efficient. By placing many accelerometers in a test vehicle, researchers are able to determine where the engine's power is being dispersed. Simple forward acceleration can be measured, of course, but so can the sideways and up-and-down shiftings within the car's frame. Automotive researchers often place a human-sized dummy containing several accelerometers inside a moving vehicle in order to determine the effect of the car's motion upon a passenger.