When it comes to understanding the fundamental units of measurement, it is important to have a clear understanding of what these units are and how they are used in various fields of science and everyday life. In this article, we will explore the concept of fundamental units and discuss which of the following is not considered a fundamental unit: kilogram, meter, second, or newton.

## Understanding Fundamental Units

Fundamental units, also known as base units, are the basic building blocks of measurement. They are the units from which all other units are derived. These units are chosen based on their relevance and importance in the physical world. The International System of Units (SI) is the most widely used system of measurement, and it defines seven fundamental units.

### The Seven Fundamental Units

The seven fundamental units defined by the SI are:

**Meter (m):**The meter is the fundamental unit of length. It is defined as the distance traveled by light in a vacuum in 1/299,792,458 of a second.**Kilogram (kg):**The kilogram is the fundamental unit of mass. It is defined as the mass of the International Prototype of the Kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures in France.**Second (s):**The second is the fundamental unit of time. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.**Ampere (A):**The ampere is the fundamental unit of electric current. It is defined as the constant current that, if maintained in two straight parallel conductors of infinite length and negligible cross-section, placed one meter apart in a vacuum, would produce between these conductors a force equal to 2 × 10^−7 newtons per meter of length.**Kelvin (K):**The kelvin is the fundamental unit of temperature. It is defined as 1/273.16 of the thermodynamic temperature of the triple point of water.**Mole (mol):**The mole is the fundamental unit of amount of substance. It is defined as the amount of substance that contains as many elementary entities as there are atoms in 0.012 kilograms of carbon-12.**Candela (cd):**The candela is the fundamental unit of luminous intensity. It is defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 × 10^12 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

## Which of the Following is Not a Fundamental Unit?

Now that we have a clear understanding of the seven fundamental units, we can determine which of the following is not considered a fundamental unit: kilogram, meter, second, or newton. The answer is **newton**.

### The Newton

The newton (N) is not a fundamental unit but rather a derived unit. It is the unit of force in the SI system and is defined as the force required to accelerate a one-kilogram mass by one meter per second squared. In other words, it is the force required to cause a mass of one kilogram to accelerate at a rate of one meter per second squared.

The newton is derived from the fundamental units of kilogram, meter, and second. It is calculated using the formula:

Force (N) = Mass (kg) × Acceleration (m/s²)

By substituting the fundamental units into the formula, we can see that the newton is not a fundamental unit itself but rather a combination of the fundamental units of mass, length, and time.

## Why is the Newton Not a Fundamental Unit?

The reason the newton is not considered a fundamental unit is that it can be derived from the fundamental units of mass, length, and time. The concept of force is fundamental in physics, but the unit of force, the newton, is not considered fundamental because it can be expressed in terms of the fundamental units.

By defining the newton in terms of the fundamental units, it allows for consistency and compatibility in the SI system. It also simplifies calculations and conversions between different units of force.

## Examples of Newton as a Derived Unit

To further illustrate why the newton is a derived unit, let’s consider a few examples:

**Example 1:**A person pushes a box with a force of 10 newtons. This means that the person is applying a force equivalent to the force required to accelerate a one-kilogram mass by 10 meters per second squared.**Example 2:**A car with a mass of 1000 kilograms accelerates at a rate of 5 meters per second squared. The force required to accelerate the car can be calculated using the formula: Force = Mass × Acceleration. In this case, the force is 1000 kg × 5 m/s² = 5000 newtons.

In both examples, the newton is used to measure force, but it is derived from the fundamental units of mass, length, and time.

## Conclusion

In conclusion, the newton is not considered a fundamental unit but rather a derived unit. The fundamental units of measurement are the meter, kilogram, second, ampere, kelvin, mole, and candela. These units are chosen based on their relevance and importance in the physical world. The newton, on the other hand, is derived from the fundamental units and is used to measure force. Understanding the distinction between fundamental and derived units is essential for accurate and consistent measurement in various fields of science and everyday life.

## Q&A

### 1. What are fundamental units?

Fundamental units, also known as base units, are the basic building blocks of measurement. They are the units from which all other units are derived.

### 2. How many fundamental units are there in the SI system?

The SI system defines seven fundamental units: meter, kilogram, second, ampere, kelvin, mole, and candela.

### 3. What is the definition of a newton?

The newton is the unit of force in the SI system. It is defined as the force required to accelerate a one-k