Analog scale is a traditional weighing scale which uses a dial marked with weight readings. The dial moves while a pointer rests on the final weight reading. An analog scale does not depend upon power supply to take the weight reading since it is a mechanical device. Conventional analog bathroom scales are widely used in homes and doctor’s clinics despite the advent of digital weighing scales.
Mechanism of an analog scale
Analog weighing scale contains four levers which evenly distribute the weight of the person standing on the scale. The levers cover the whole cross section of the scale and anyone standing on the machine exerts pressure on the four levers. The levers end are connected to an end plate which houses the main spring assembly of the scale. The spring assembly is, in turn, connected to the dial with weight markings.
When you stand on the platform of the weighing scale, you exert force on the levers which cause the spring assembly to move the dial. More the force you exert on the levers, more the dial will move. In other words, the movement of the dial is proportional to the weight exerted on the levers, i.e. weight.
Another spring assembly is also present in an analog weighing scale. It is used to calibrate the scale to zero.
Analog weighing scale uses Hooke’s law to give the weight reading. Hooke’s law provides the relation between weight and the extent of stretching of a spring.
Hooke’s law states that F=kx where F is the force, k is spring constant and x is the extent of deflection of the spring caused by the force.