**Unit of mass –** Hello *Sinaumed’s* friends , Did you know? The unit of mass is one type of unit that is commonly used in everyday life.

The most well-known unit of mass is the kilogram. You must have often heard that kilograms are widely used to measure the weight of an object.

For example, in kitchen needs such as sugar, eggs, flour, everything is measured or weighed in kilograms of mass. Check out the review of getting to know mass units to learn together, Sinaumed’s!

**Definition of Unit of Mass**

A unit of mass is a unit used to measure mass. Mass is a physical property of an object that is used to explain various observed object behaviors.

In everyday life, mass is always synonymous with weight. But in reality, mass and weight are different. The weight is caused by the interaction between the mass and the Earth’s gravitational field.

For example, an object with a weight on earth, when it is sent into outer space or to another planet, the object has no weight because there is no gravity. However, the object still has the same mass.

For example, a person lifting a heavy object on Earth could relate the object’s weight to its mass. This alignment is acceptable for objects on Earth. But if the object is on the Moon, then the weight of the object will be less, it will be easier to lift, but the mass will remain the same.

The human body is equipped with taste buds that allow us to feel various phenomena related to mass. One can observe an object to determine its size, lift the object to feel its weight, and push it to feel its inertia.

These senses are part of our understanding of mass, but none of them fully express the abstract concept of mass. Abstract concepts do not come from the senses, but from a combination of many different human experiences.

**Mass Units**

One kilogram (1 kg) is the standard for measuring mass. The weight of one kilogram is determined by the mass of the cylinder made of platinum-iridium alloy. The standard instrument for determining mass is kept at the International Bureau of Weights and Measures in Sèvres, France. Strict and controlled maintenance of anti-damage metal vessels. The definition of standard mass has not changed since its inception. Copies of standard volumes are produced by several countries and maintained at the metrology offices of each country. One country that has doubled the mass of the standard kilogram is the United States. This copy is kept at the National Institute of Standards and Technology.

The standard unit of time was established in 1967 at the 13th Conference on Weights and Measures. The results of the conference determined that one second was based on the frequency of the light waves emitted by a cesium atom. The standardization of the cesium atom is due to the fact that the frequency of the emitted waves can be easily generated and can be measured with very high accuracy.

The vibration of the cesium atomic beam occurs 9,192,631,770 times per second. So, one second is defined as the time it takes for a beam of light from a cesium atom to vibrate 9,192,631,770 times.

Standard time was set by making atomic clocks based on wave oscillations emitted by cesium atoms. The first atomic clock is kept at the National Institute of Standards and Technology, USA. In 30,000 years, there will only be one mistake. Atomic clocks are now installed on every Global Positioning System satellite orbiting Earth from space.

The tool used to measure mass is usually a scale. In SI units, mass is measured in kilograms, kg. There are also various other units of mass, for example:

- grams: 1 g = 0.001 kg (1000 g = 1 kg)
- tons: 1 ton = 1000 kg
- MeV/c2 (Generally used to observe the masses of subatomic particles.)

Under normal circumstances, the weight of an object is proportional to its mass. But the difference between mass and weight is necessary for high-precision measurements.

Because of the relativistic relationship between mass and energy, it is possible to use units of energy to represent mass. For example, eV is normally used as a unit of mass (approximately 1.783×10−36 kg) in particle physics.

To measure mass units, there are two tools that can be used, namely as follows.

**1. Scales**

Scales are measuring instruments used to measure mass using a spring, usually a mass measuring instrument in the form of a balance that uses a spring or a spring to operate the balance.

The function of the scales is used as a household tool or body scales. Scales are often used to prepare dishes or cakes from recipes. Scales are also a tool for weighing the body on a larger scale.

**2. Balance sheet**

The balance uses the principle of balance between the load on one side and the load on the other. The use of balances is often found in markets or shops that sell per kilogram (sell per object weight). The object or load to be measured is placed on one side of the balance.

On the other hand, weight is defined as a measure. So there is a balance between this side and the other side. Several types of balances include a two-handed balance and a three-handed balance (OHaus Balance). A two-handed balance can measure mass more accurately, such as measuring the mass of gold, silver and others in grams.

Arm balances are usually used to buy and sell valuables such as gold and silver. The OHaus balance is usually used in the laboratory with an accuracy of 1 gram. The OHaus balance is known as a three-pronged balance. Using the OHaus balance involves moving a load across the three scale arms until balance is reached.

At present, there is a type of balance with an electronic operating principle called electronic balance. Electronic scales are commonly used in modern markets such as supermarkets or commercial centers.

The way to use an electronic balance is to place an object with a mass to be measured in the charging area of the electronic device. Next, a number will appear indicating the mass (or weight) of the object being measured.

**How to Convert Mass Units**

The unit of mass in the International System of Units (SI) is the kilogram with the symbol kg. This unit is commonly used in all countries. Scientists chose the kilogram as the unit of mass in 1889. First, scientists debated which unit of mass to use.

Then it was agreed that 1 kilogram (kg) is equivalent to an object measuring 4 centimeters (cm) with a composition of 90% platinum and 10% iridium. Only after that was agreed by the parties and began to be distributed to all countries in the world as a standard size of an object.

Trade is one sector that uses the kilogram as a unit of mass measurement the most. The unit of mass in kilograms has its own series in the form of a mass scale.

For more details, Sinaumed’s can immediately see the mass unit scale below.

From the mass unit scale it is known that the upper order is kg with the largest value. As for the lowest scale, the milligram (mg) is the smallest unit of mass.

For more details, the order of mass units is as follows:

- Kilograms (kg)
- Hectograms (hg) or ounces
- Decagram (dag)
- grams (grams)
- decigrams (dg)
- Sentiment (cg)
- Milligram (mg)

On the bulk scale, if you go one step down, you multiply by 10.

But if you go up one step, it must be divided by 10.

Before converting mass units, *Sinaumed’s* must pay attention that in this mass conversion, certain weight units are usually used, such as dumbbells and tons.

Weight is per kilogram, tons per kilogram and dumbbells are on the scales.

1 quintal = 100 kg

1 ton = 1000 kg

In addition to weight and tons, pounds appear when converting units of mass to units of weight. Because the pound itself is equivalent to 5 ounces.

1 pound = 5 ounces (hg)

1 kg = 2 pounds

This is because from kilograms to hg (ounces) you have to subtract one order, so you have to multiply by 10.

**Examples of Mass Unit Problems**

To make conversion calculations easier, of course, *Sinaumed’s* practices by asking questions. There are many variable mass units that we may encounter. Here there will be many examples of questions with different variables that can be done by *Sinaumed’s,* as follows.

**Example Question 1**

Example question 1

Father bought 2 kg of rice, how many grams of rice did mother buy?

**Answer:**

The first problem is the easiest problem that *Sinaumed’s* can solve because you just need to multiply it.

Judging from the mass unit ladder, the kg is three levels above the gram. If you want to convert kg to grams, you have to go down three steps so that later the kg will be multiplied by 1,000.

2 kg x 1,000 = 2,000 grams.

**Example Problem 2**

Yesterday my sister bought canned milk at the supermarket. In the can of milk, the time is stated, namely net 400 g. Express the mass in kg and mg units!

a) 400 grams =… kg

From g to kg increase 3 steps then divide again by (10) 3 = 1000, so:

400g = 400 / 1000kg = 0.4kg

b) 400 g = … mg

From g to mg, go down another 3 steps and then multiply (10) 3 = 1000, so:

400g = 400 x 1000mg = 400,000mg

There are also unit conversions that apply in some countries. This unit can be converted to kg, namely:

1 pound = 0.454 kg

1 ton = 1000 kg

1 quintal = 100 kg

1 ounce (oz) = 0.02835 kg

1 pound (lb) = 0.4536 kg

1 slug = 14.59 kg

**Example Problem 3**

Brother pours 600 grams of toy sand, how many ounces of toy sand does younger sibling have?

**Answer:**

The units of mass used in this problem are grams and ounces. In the mass unit ladder, from grams to ounces (hg) has to go up two ladders. So grams must be divided by 100.

600 grams : 100 = 6 ounces (hg)

**Example Problem 4**

A trader has 5 tons of sugar. He had sold it for 34 quintals.

How many kg of sugar does the trader have now?

**Answer:**

For the last example, this question is a bit complicated because it involves kg, tons, and quintals. In order to do it easily, *Sinaumed’s* needs to equate the unit first to kg.

5 tonnes = 5 x 1,000 = 5,000 kg

34 quintals = 34 x 100 kg = 3,400

From here Moms can do calculations easily. If you read it again, the question given will be that a trader has 5,000 kg of granulated sugar and has sold 3,400 kg.

So the remainder is 5,000 kg – 3,400 kg = 1,600 kg. That is an explanation of the unit of mass that *Sinaumed’s* needs to know so that later it can be easily taught to others.

**Difference between Mass and Weight**

There is a difference between mass and weight. Mass is an intrinsic property of matter. It doesn’t change depending on where you measure it. It is a scalar value, meaning it has magnitude, but no direction associated with it.

The mass of an object is never zero. You measure mass using normal equilibrium on Earth or inertial equilibrium in outer space.

Weight depends on the effects of gravity, so it can vary depending on where it is measured. In the absence of gravity, the weight could be zero. Since weight is a force, it is a vector. It has magnitude and direction. You measure your weight on a spring scale.

**Units of Mass and Weight**

We tend to measure weight in grams, kilograms, ounces, and pounds. Technically, grams (g) and kilograms (kg) are units of mass. The SI unit for weight is the Newton (N), with a mass of 1 kg exerting a force of 9.8 N on Earth. The US unit of weight is the pound (lb), while the unit of mass is called the slug. A pound is the force required to move the mass of the snail at 1 ft/s 2. The weight of the snail is 32.2 pounds.

While it is acceptable to use pounds and kilograms interchangeably in most practical cases, in science it is preferable to use kilograms for mass and Newtons for weight.

**Mass Concepts**

In physics, we can conceptually distinguish at least seven types of mass or seven physical phenomena that can be described using the concept of mass:

**Inertial mass** is a measure of the ability of an object to change its state of motion when a force is applied. It is determined by applying a force to an object and measuring the acceleration produced by that force. An object with a low inertial mass will accelerate faster than an object with a high inertial mass. It can be said that the greater the mass of an object, the greater its inertia.

**The amount of matter** in a particular type of sample can be determined accurately by electrical deposition or other processes. The exact mass of a sample is determined by counting the number and types of atoms it contains. In addition, the energy involved in the bonding of these atoms is also calculated (responsible for the lack or loss of mass).

**Active gravitational mass** is a unit of measurement for the strength of gravitational currents. The gravitational field can be measured by letting an object fall freely and measuring the free fall acceleration of the object. For example, an object free-falling on the Moon would receive less of a gravitational field, so it would accelerate more slowly than if the object were free-falling on Earth. The Moon’s gravitational field is weaker because the Moon has a smaller active gravitational mass.

**Passive gravitational mass** is a measure of the strength of the interaction of an object with a gravitational field. Passive gravity is determined by dividing the mass of the object by the free fall acceleration of the object itself. Two objects with the same gravity will have the same acceleration. However, an object with a smaller passive gravitational mass will experience a smaller force (it weighs less than an object with a larger passive gravitational mass).

**Energy** also has mass according to the principle of mass-energy equivalence. This equality can be seen in nuclear fusion and gravitational lensing. In nuclear fusion, some of the mass is converted into energy. In a gravitational lens, photons with energy exhibit a behavior similar to that of a passive gravitational mass.

**The bending of space-time** is a relativistic manifestation of the existence of mass. This curvature is very small and difficult to measure. Therefore, this phenomenon was discovered only after Einstein’s general theory of relativity predicted it. Highly accurate atomic clocks have been found to run on Earth more slowly than atomic clocks running in outer space. This time difference is called gravitational time dilation.

**Quantum mass** is the difference between the quantum frequency of an object and its wave number. The quantum mass of an electron can be determined using a variety of spectroscopic methods and primarily involves the Rydberg constant, the Bohr radius and the classical electron radius. The quantum mass of larger objects can be measured directly on the watt scale.