Accelerometer

Accelerometer, device used to measure acceleration, working on the principle expressed by Newton's law: a = F/m, where a = acceleration, F = force, m = mass. The accelerometer measures the force expressed on a spring by an object of known mass. When acceleration takes place, the object is forced back against the spring as passengers in a car are pressed against the back of their seats. The greater the acceleration, the more the object is forced back. The distance the object moves back, measured in an electrical circuit, is a measure of the acceleration.