The acceleration of a falling ball

The change in speed per second of a moving body is called the acceleration. When it is constant as in the case of a ball falling under the action of the earth's gravity, it can easily be measured. In this particular case it is generally shown by the symbol g. In the following experiment, the fall of a metal ball is intercepted by a lath about 120 cm long fluctuation from a nail fitting loosely onto a hole hear one end.