ABSTRACT
Electronic scales typically use a strain gauge to measure weight or force. Most strain gauges are resistive. A resistive strain gauge consists of a very thin resistor mounted on a material that will flex as force is applied. A force applied to the resistor will deform it slightly, resulting in a change in its resistance. Something that is massive and moving fast has a lot of momentum. Momentum is a vector because it has both magnitude and direction. A simple force gauge can be made from a spring. In order to stretch or compress a spring, a force is needed. The amount by which the spring changes length is determined by the force. The mass of an object is the same everywhere because the amount of matter contained in it stays the same, but weight is gravity-dependent, that is, an astronaut weighs less on the moon because gravity is smaller.
