The SI Units, the International System of Units is generally used in the world of Trade, Science and Engineering. The International System of Units comprises of logical set up of measurement units that start with seven base units.
We all know who Sir Isaac Newton was and his contribution. He was an English mathematician, Physicist, Astronomer, Alchemist, Theologian, and Author. He was also described as a “Natural Philosopher” in his times.
It was the work and research of Sir Isaac Newton which led to the establishment of the popular relation between Force, Mass, and Acceleration. He came up with the popular formula “F = ma”. The ‘a' in the formula represents acceleration, and ‘m' is the mass of an object when force ‘F' is applied on it. Here in this article, we will read more about what the SI Unit of Force is and the role of mass and acceleration in it.
SI Unit of Force
The SI Unit of Force is Newton (N). This symbol ‘N' represents force. The base units which are relevant to force are metre, kilogram, and second.
- The 'metre', unit of length — symbol m
- The 'kilogram', unit of mass — symbol kg
- The 'second', unit of time — symbol s
What is Force?
The answer to What is Force, in simple words, Force is the Physical Strength or Power, which can make somebody do something that he/she/it does not want to. It is the physical strength to do or move something.
- Force can also make an object with mass to change its velocity i.e. it can make the object to accelerate. Force is a vector quantity as it has both direction and velocity.
- Force is one of the quantities such as pressure, energy, momentum, etc that have a unit they shall be measured in. The Unit of Force can be different depending on the different systems of measurements.
What are the Effects of Force?
Change in state of the body of position
- To change the speed of the body
- To change the direction of the body
- To accelerate the moving body
- To decelerate or bring it to stop
Calculation of SI Unit of Force:
When we get more into the Physical Dimensions, Force is usually measured by MLT-2. While talking practically, we do not consider the mass of the object instead we take into account the weight of the object. The basic unit of force, therefore, is given as:
The SI Unit of Force is ‘Newton' and the symbol used to denote Newton is ‘N'. The basic unit of Force using the basic units which are relevant of force such as metre, Kilogram, and second is:
F = (W/g)LT-2
where W represents the weight whereas g represents the acceleration.
Definition of Force
Force is also defined as the rate of change in momentum. For a never changing mass, this will be equivalent to mass multiplied by acceleration. This gives,
1 N = 1 kg m s-2, or 1 kg m/s-2
More About SI Unit of Force
Newton's Second Law of Motion states that the Force is defined or expressed as the product of Mass of an object and its acceleration.
In both the systems i.e. the SI System (the International System of Units) and the MKS system, the SI Unit of Mass is kilogram, which is abbreviated as kg and the SI Unit of Acceleration is m/s2. Deriving the SI Unit of Force using these three units will get you kg m/s2. The unit of force is expressed as N which stands for Newton.
- In the CGS System of Units, the unit of mass is gram denoted as g, and the unit of acceleration is cm/s2. This means the CGS Unit of Force is g cm/s2, which is known as dyne or Dyn.
- According to the FPS System of Units, the unit of Mass is pound of lb and the unit of acceleration is feet per second squared or ft/s2. Hence, the FPS Unit of Force is lb-ft/s², which is called poundal or pdl.
Derivation of SI Unit of Force
The Force Formula Derivation is given below in this article. Since we know that Force is a product of Mass and Acceleration. Force is a vector quantity as it has both magnitude and direction. The Formula of Newton's Second Law of Motion is –
F = ma
Force (F) = Mass (M) * Acceleration (A)
What is Acceleration?
Acceleration is defined as the rate of change of Velocity (v) of an object in a particular specified time (t). We can express acceleration as:
a = vt
Acceleration (a) = Velocity (v) * Time (t)
So, we can write Force as,
F = mv/t
It is known that P = mv where p is the momentum.
Therefore,
F= p/t = dp/dt
Force formula is considered helpful when calculating force, mass, acceleration, momentum, or velocity in any given problem.
Points to Ponder
- the SI Unit of Force is Newton ‘N'
- SI Unit of Mass is Kilograms ‘Kg'
- SI Unit of Acceleration if Metre/Second2
Types of Forces
There are two types of forces i.e. Contact Forces and Non-contact Forces –
- Contact Forces
- These are the forces that are directly in touch with the body where the force is being applied or the area which is in touch through a medium. The examples of Contact Forces are Muscular Forces, Mechanical Forces, and Frictional Forces.
- Non-contact Forces
- These are the forces that act without any medium or any direct contact with the body the force is applied to. The examples of these forces are Magnetic Forces, Electrostatic Forces, and Gravitational Forces.
Other Units of Force
When the mass of a body is subjected to an acceleration, the force applied on the body is known as poundal and the term is denoted as pdl. We will have the pound-force which is a gravitational unit of force. This gravitational unit of force is denoted as ‘lbf' and these are the units of measurement in the FPS System.
In the metric system, the force is calculated in the terms of Kilograms which is denoted as ‘kgf'. CGS System is another measuring system which is a relatively smaller measure. In the CGS system the unit of force is measured in dynes and it is dented as ‘gf'.
The other units of force are given below:
Unit | Denoted as | Equivalent Newton Unit |
Dyne | dvn | 10-5 N |
Gram Force | gf | 9.80665 mN |
Poundal | pdl | 138.2550 mN |
Pound – Force | lbf | 4.448222 N |
Kilogram – Force | kgf | 9.80665 N |
SI Units
The International System of Units is a globally accepted metric system which was established in the year 1960. It is internationally known as the standard for measurement which is approved by scientific researchers. It makes it easier for people to understand or express the quantity of any natural phenomenon.
The SI Units hold importance as they are based on precisely set standards and the base used in SI units is 10. The calculations made keeping 10 as base makes them easier.
There are a total of 7 base units and 22 derived units.
Quantity | SI Unit | SI Unit Symbol |
Length | Metre | m |
Mass | Kilogram | kg |
Time | Second | s |
Electric Current | Ampere | A |
Thermodynamic Temperature | Kelvin | k |
Amount of Substance | Mole | mol |
Luminous Intensity | Candela | cd |
Also read more about the SI Unit of Electric Current.
What is the SI Unit of Gravitational Force?
The gravitational force is the universal force of attraction that acts between objects. The SI Unit of Gravitational Force is as same as that of the SI Unit of Force. The SI Unit of Gravitational Force is Newton and it is represented as ‘N'. Besides, the SI Unit of Mass is Kilogram which is denoted by ‘kg'.
Note* The gravitational force between two objects with two different masses i.e. M and m which are separated at a distance ‘r' is:
F = GMm/r2
What is the SI Unit of Moment of Force?
In order to answer this question, students must know ‘What is Moment of Force?'. The moment of force is defined as the product of perpendicular distance and force from the axis. Now that distance and force are involved, the SI Unit of Moment of Force is Newton – Meter which is denoted as ‘Nm'.
What is the SI Unit of Electromotive Force?
The SI Unit of Electromotive Force is Volt. The Electromotive Force is numerically defined as the number of energy Joules is given by the source divided by each Coulomb to enable a unit electric charge to move along the circuit.
Note* The SI Unit of Electromotive Force is Volt which is denoted by ‘V'.