October 1, 2022 If you’ve ever bought groceries at the market, then you’ve probably used a weighing scale to determine how much of your chosen item to buy. You may have noticed that most of these scales display weight in kilograms or pounds, not grams or ounces, and wondered why that was the case. In order to understand this, you need to know how weighing scales measure weight to begin with.

## The concept behind weighing scales

Weighing scales have been a part of our society for years, but you may not know how they work. They measure weight by measuring the amount of force exerted on the load cell. The load cell then converts that result to mass and displays it in various units of mass. If they didn’t convert it to kilos or pounds, the number would be very difficult to read or decipher. The International System (SI) defines 7 types of mass: Kilogram, meter-kilogram, gram, liter-kilogram, milligram, microgram, and nanogram. All measurements are standardized to one type of mass measurement unit called the kilogram (kg).

### What are weighing machines?

Weighing machines measure weight by measuring the amount of force exerted on the load cell. They then convert that result to mass and display it in various units of mass. If they didn’t convert it to kilos or pounds, you would get a decimal number. That’s why weighing scales and balances need some kind of conversion to show results in pounds or kilograms. It might seem odd for Digital Weighing Machine to have such advanced math capabilities, but it does make sense considering their function.

The first sentence about converting numbers is inaccurate because any type of scale will be capable of doing this process regardless if the unit of measurement is kilograms or not.

#### The difference between force and pressure

There is a difference between force and pressure. Pressure is the amount of energy exerted per unit area, while force is the amount of energy exerted per unit area and there are many types of forces. One type of force that can be measured with scales and balances is gravity. When measuring weight (mass), you would need to measure not only how much something weighs but also how heavy it is. A kilogram on Earth has the same mass as a kilogram on Mars, because they have different levels of gravity, but they have different weights because they are located in different places on their respective planets.

#### Centripetal forces

If it wasn’t for centrifugal forces, the mass would be determined by measuring the force exerted on a load cell. Load cells are devices that measure the amount of force exerted on them. If you use a balance beam with one side being heavier than the other, then when you place your object on that side, it will push down on the load cell and release a value that corresponds to its weight. The other side would be empty and would not push down at all.

#### Newton’s laws of motion

Newton’s first law of motion is often called the law of inertia, which means an object will remain at rest or continue moving with constant velocity unless acted upon by an external force. Newton’s second law states that the net force acting on a body equals the mass times its acceleration. It is important to know these two laws to understand how weighing scales work.

#### Comparisons between measurement techniques

Weighing scales and balances measure weight by measuring the force exerted on the load cell. They then convert that result to mass and display it in various units of mass. If they didn’t convert it to kilos or pounds, the units would be ounces or grams. The most common measurement type is kilograms as this is what we measure weight every day. In order to know how much a person weighs in kilograms, you need to divide their weight by two times their height squared. For example, a person who measures 5’5 (65 inches) will weigh 98kg if they are roughly average height for an American male.

#### Air resistance

The air resistance will result in a difference between the reading on the scale and the actual weight. This can be compensated for by subtracting the reading from what it would have been without air resistance.

#### Direct comparison with air pressure measurement methods

Electronic Weighing Machine and balances measure weight by measuring the force exerted on the load cell. They then convert that result to mass and display it in various units of mass. If they didn’t convert it to kilos or pounds, we would have no way to compare these measurements with air pressure measurements because air pressure measurements are only ever reported in air pressure units. In contrast, a weighing scale can be converted into something completely different, but still, measure the same thing- weight.