A spring scale is a weighing scale use to measure force, such as the force of gravity, exerted on a mass or the force of a person's grip or the force exerted by a towing vehicle. This force is commonly measured in newtons, for which one newton corresponds to the weight of about a tenth of a kilogram of mass, or about the weight of an apple. The spring scale can also be correctly called a Newton Meter, because it is used to measure newtons.