Unit of Mass SI Unit (original) (raw)
Last Updated : 23 Jul, 2025
Unit of Mass is a standard quantity used to measure the amount of matter in an object. The SI unit of mass is kilogram (kg). Other common units of mass include the gram (g), tonne (t), pound (lb), etc. Mass plays a crucial role in our daily lives, influencing our understanding of the physical world and contributing to various scientific and practical applications.
In this article, we will learn about mass, unit of mass in different systems, SI unit and CGS unit of mass, Conversion of mass unit, and some solved examples based on it.
Table of Content
Definition of Mass
Mass is the measure of the amount of matter in an object. It is an intrinsic property that is independent of an object's location and is often considered synonymous with "weight", However, weight and mass are two different physical quantities.
Mass can be categorized into different types based on the state or form of matter:
- **Solid Mass: Refers to the mass of objects that maintain a fixed shape and volume, such as a book or a brick.
- **Liquid Mass: Describes the mass of substances that take the shape of their container but maintain a constant volume, like water or oil.
- **Gas Mass: Represents the mass of substances that conform to both the shape and volume of their container, like air or helium.
What is Unit of Mass?
The unit of mass is a measure of the amount of matter in an object. In simpler terms, Unit of mass quantifies the substance or material contained within an object. **In the International System of Units (SI), the base unit of mass is the kilogram (kg).
Other common units of mass include the gram (g), metric ton (t), pound (lb), ounce (oz), and others, depending on the system of measurement being used.
Formula of Mass
The formula for mass is a measure of the quantity of matter in an object. The mass (m) is determined by
**m = ρ × V
where,
- m = mass
- ρ = Density of the substance,
- V = Volume occupied by the substance.
This formula is based on the definition of density, which is the mass per unit volume of a substance.
What is 1 Kilogram?
The kilogram is the base unit of mass in the International System of Units (SI), having the unit symbol kg.
**1 kg = 1000 g
SI Unit of Mass
The SI unit of mass is Kilogram. It is used universally to measure mass in scientific contexts and daily life.
**SI unit of mass is the Kilogram (g).
**Note: The gram is a small unit, and for larger masses, prefixes such as kilograms (kg) are commonly used.
Unit of Mass in Other Systems
While the SI system uses the kilogram as the primary unit of mass, other systems employ different units. Here are some common units and their equivalents:
| System | Unit |
|---|---|
| CGS (Centimeter-Gram-Second) | Gram(g) |
| MKS (Meter-Kilogram-Second) | Kilogram(Kg) |
| **Imperial System | Pounds(lb) |
| **British Gravitational System | Slug |
Some other unit of mass with their equivalent value in SI is given below:
| Unit | Equivalent Value |
|---|---|
| Metric ton or Tonne (t) | 1000 kg |
| Pound (lb) | 0.4536 kg |
| Ounce (oz) | 0.0283495 kg |
Relative Mass
When the velocity (_v) of the object approaches the speed of light (_c), the Lorentz factor (?) increases, causing the relativistic mass (_m) to increase significantly compared to the rest mass (__m_o). This phenomenon is a fundamental aspect of special relativity and is described by the formula:
**m **= **γm**o
where
m = relative mass of an object.
mo = rest mass of the object.
? = Lorentz factor, which is a dimensionless quantity that depends on the object's velocity.
Unit of Relative Mass
Relative mass (m) is given by the formula **m **= **γm**o, therefore, the unit of relative mass depends upon γ and mo.
So, Unit of relative mass(m) = unit of γ × unit of mo
Now, we know, γ (Lorentz factor) is dimensionless and unit of mo is Kg
Hence, **the unit of relative mass is also kg.
Conversion Between Units of Mass
The following table provides conversion factors for various mass units:
| From/To | Milligram (mg) | Centigram (cg) | Decigram (dg) | Gram (g) | Decagram (dag) | Hectogram (hg) | Kilogram (kg) |
|---|---|---|---|---|---|---|---|
| Milligram (mg) | 1 | 0.1 | 0.01 | 0.001 | 0.0001 | 0.00001 | 0.000001 |
| Centigram (cg) | 10 | 1 | 0.1 | 0.01 | 0.001 | 0.0001 | 0.00001 |
| Decigram (dg) | 100 | 10 | 1 | 0.1 | 0.01 | 0.001 | 0.0001 |
| Gram (g) | 1000 | 100 | 10 | 1 | 0.1 | 0.01 | 0.001 |
| Decagram (dag) | 10,000 | 1000 | 100 | 10 | 1 | 0.1 | 0.01 |
| Hectogram (hg) | 100,000 | 10,000 | 1000 | 100 | 10 | 1 | 0.1 |
| Kilogram (kg) | 1,000,000 | 100,000 | 10,000 | 1000 | 100 | 10 | 1 |
To convert a value from one unit to another, multiply by the corresponding factor in the table. Here are a couple of examples:
Example 1: Convert 500 grams to kilograms.
As per the table above: 1g = 0.001 kg
Therefore, 500 g = 500 × 0.001 kg = 0.5 kg
Example 2: Convert 2,500 milligrams to grams.
As per the table above: 1mg = 0.001 g
Therefore, 2500 mg = 2500 × 0.001 g = 2.5g
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Sample Problem on Unit of Mass
Problem 1. Convert 3.5 kilograms to grams.
Solution:
To convert 3.5 kilograms to grams, use the conversion factor:
1 kg = 1000 g
So, to convert 3.5 kg to g:
3.5 × 1000 = 3500g
Therefore, 3.5 kg is equal to 3500 g.
Problem 2. Convert 500 grams to kilograms.
Solution:
To convert 500 kilograms to grams, use the conversion factor:
1 kg = 1000 g i.e.,
1 g = 1 / 1000 kg
So, to convert 500 g to kg:
500 / 1000 = 0.5 kg
Therefore, 500 g is equal to 0.5 kg.
Practice Problems on Unit of Mass
**Problem 1. Convert 800 grams to kilograms.
**Problem 2. Convert 0.5 slugs to kilograms.
**Problem 3. Convert 1200 kilograms to slugs.
**Problem 4. Convert 5 slugs to grams.
**Problem 5. Convert 2 kilograms to slugs.