Mechanical weight scale working principle:
Figure 1: Beam balance scale
A weighing scale is one of the devices to measure weight. The prime structure of a weighing scale consists of a beam with a fulcrum system at its center. To alter the weight of a certain object, an object with a certain amount of weight was hung on one end of the beam while the unknown weight object was hung on the other end. For a better or precise result, the center beam balance is still one of the most accurate technologies available, and is commonly used to calibrate or measure the weight of an object.
An example of the working principle of weighing scale is a beam balance scale (Figure 1). The beam balance is a first order lever with fulcrum in the middle while two pans were at the end of each side of the beam balance. An object is placed on one of the pan, to make sure the beam is balance, the same amount of weight were put on the other end of the pan. When an object was place on one of the pan, a gravitational force will act on the pan, F=mg, which makes the pan go downward because of the force exerted on the pan. And when the other end of the pan were added the same amount of force, F2, the pan with the object will rises and the beam will be balance because the exerted force have been equal. This is represented in the form of equation, F1 = F2, where F1 is the force exerted by the object and F2, is the force exerted to make the pan balance. The amount of force exerted to make the beam balance is the real weight of the object measured.