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Unit of Weight: SI Unit, CGS Unit, Other Unit and Unit Conversion

Samiksha Gupta

Updated on 20th March, 2023 , 6 min read

SI Unit of Weight Overview

Newton (N) is the SI unit of weight in physics. As weight is measured in both the unit of force, the Newton (N), and the standard base unit, the kilogram (kg), the measurement of weight can be confusing. 

  1. Gravitational force is referred to as weight and acts on a body.
  2. As a result, the si unit of weight and force are the same.
  3. Newton (N) is the weight unit in the SI.
  4. 1 Newton of weight is equal to kg/m/s2, the unit of weight measurement. 
  5. Markets frequently measure an object's weight in kilograms (kg), which is used to gauge how heavy it is.

What is Weight?

Simply put, an object's weight is the amount of force that the Earth's gravitational field uses to pull it towards the surface. In other words, weight is the rate of acceleration of a body toward the Earth's surface as a result of its gravitational pull. It is expressed as w= mg, where

  1. w:  Weight of the Body
  2. m:Mass of the Body
  3. g: Acceleration due to Gravity

You are aware that everything suspended in the air falls to the ground. This planet's gravity field makes it possible for objects to fall to the ground, which is the cause of the phenomenon. When you hold a ball or an egg higher than the ground and then release your hold, for instance. You witness that it immediately drops to the ground. 

 In order to express the numerical value of the force that pulls an object toward the ground, the SI unit of weight was created. 

Also read about- Ohm's Law and What is Friction?

SI Unit of Weight Highlights

Following are some of the highlights of si unit of weight:

Particulars

Details

Common symbols

W

SI unit

newton (N)

Other units

pound-force (lbf)

In SI base units

kg⋅m⋅s−2

Extensive?

Yes

Intensive?

No

Conserved?

No

Derivations from

other quantities

W= mg

W= ma

Dimension

MLT−2

Understanding Weight

Weight is the amount of force that the gravitational field uses to pull an object toward the surface of the earth.

We are all aware that the center of gravity pulls all objects towards it with a force. The unit of weight is a measure of how much force is needed to push an object toward the surface of the earth.

What is the SI unit of weight? 

Imagine that a 1 kg object experiences a 1 m s-2gravitational force as it falls vertically to the ground. If you're wondering what the unit of weight is right now, it is the sum of all these parts. 

Therefore, weight = mass X gravity. 

The object's weight in this instance is - 

1 kg X 1 m s-2= 1 kg m s-2

The accepted unit of weight is kg m s-2. You can also translate it into Newtons (N), though. The eponymous unit is named for the renowned scientist Isaac Newton, who made the initial discovery of gravitational pull. 

The SI unit of weight is therefore referred to as a Newton (N). 

Also read about- Difference between Interference and Diffraction

What is the alternative SI unit of weight?

  1. Weight Dimensional Unit: MLT-2, where M stands for mass, L for length, and T for time. 
  2. CGS Unit of Weight:  Dyne. Weight equals 1 g cm s-2in the centimeter-gram-second (CGS) unit. You can also arrive at dyne when you divide 1 Newton by 10000. 
  3. Weight Base Unit: The base unit of weight is kg m s-2because that is the unit we previously discussed.. 

SI unit

N

SI base unit

kg.m.s-2

CGS

dyne

Dimension

MLT-2

Also read about- Law of Variable Proportion

Metric Conversion of Units of Weight

The gram is one of the most widely used weight measurement units. The following standard denominations are used to convert one gram to one kilogram:

1 g = 0.001 kg

1 mg = 0.000001 kg = 0.001 g

1 centigram = 0.00001 kg = 0.01 g

1 metric ton = 1000 kg

Understanding Mass

The volume of material that makes up an object is referred to as its mass. Although mass and weight have distinct meanings, they are occasionally used interchangeably. It is known as the quantitative measurement of inertia.

The mass, in contrast to the weight, has a constant value that is unaffected by variations in gravitation. Both a kilogram and a gram can be used to represent it. Therefore, a body with a mass of 70 kg on Earth will have the same mass on the Moon whether gravitational pull is present or not.

Also read about- SI Unit of Electric Flux and SI Unit of Electric Current.

Relation Between Mass and Weight

Force (F) equals the product of mass (M) and rate of acceleration (rate of acceleration) (A) in accordance with Newton's Second Law of Gravitation. 

F= MA

Even though the mass does not change, gravitational changes cause the weight to change. A person's weight will therefore vary greatly between Earth and the Moon. 

Also read about- Difference between Real Image and Virtual Image

What is the Difference Between Weight and Mass? 

People who frequently use the terms "weight" and "mass" interchangeably. However, the scientific meanings of these two terms differ significantly.  In simple terms, mass refers to the amount of matter that an object possesses.  

Weight, on the other hand, denotes the force an object experiences as it approaches the earth's surface. It suggests that weight differs for an object as per alterations in the gravitational pull. 

For instance, an astronaut's mass is constant on both the earth and the moon. However, the moon has a 6 times weaker gravitational pull than Earth. An astronaut will therefore weigh six times less on the moon than they would on Earth. 

Mass

Weight

The amount of matter that makes up an object has mass.

Weight is the pull an object experiences as it moves toward the center of gravity.

The kilogram (kg) is the SI unit of mass.

Newton (N) is the weight unit in the SI.

Since mass has only magnitude and no direction, it is a scalar quantity.

Weight has both a direction and a magnitude, making it a vector quantity.

The gravitational forces have no effect on mass.

Due to gravitational forces, weight changes. 

There can never be no mass.

If there is no gravitational force, weight can be zero. 

Never can mass be zero.

Compression balance or spring balance are used to measure it.

Also read about- Father of Physics

Things to Remember

  1. Weight is the force of gravity acting on the object.
  2. It is the result of mass and gravitational acceleration.
  3. W = mg, where m is the mass and g is the gravitational acceleration, is the formula for weight.
  4. Newton (N) is the weight unit in the SI.
  5. The heaviness of an object is also determined by its weight, which is expressed in kilograms (kg).
  6. Additional weight measurements include dyne, pound-force, slug, and gram.
  7. In physics, an object's weight is inversely proportional to its mass.

Also read about- Surface Tension Formula

Other SI Units Lists

The following are a few of the basic units listed in the table: 

Physical Quantity

SI Unit

Symbol

Time

Second

s

Electric Current

Ampere

A

Length

Metre

m

Mass

Kilogram

kg

Amount of Substance

Mole

mol

Temperature

Kelvin

K

Luminous intensity

candela

  Cd

Also read about- SI Unit of Sound, SI Unit of Impulse & SI Unit of Acceleration

Sample Questions of SI unit of weight

Question 1. What is the SI unit of weight? 

Solution. The weight unit in the SI is the Newton (N). Since weight is defined as the force an object exerts, it is derived from the unit of force. Isaac Newton, who was the first to discover gravitational pull, is honored by having his name attached to the unit. 

Question 2. What is weight?

Solution. Weight, which can be calculated as mass times the acceleration of gravity, is the gravitational force acting on the object. It is expressed as 

w = mg

The object's mass, m, and gravitational acceleration, g, are both present in this situation.

Question 3. What is the CGS unit of weight? 

Solution. The CGS weight unit is called a dyne. Weight is measured as 1 g cm/s2 in the centimeters-grams-second (CGS) unit. By multiplying by 10,000, one Newton can be changed into one dyne.

Question 4. List the other units of weight. 

Solution. Aside from the SI Unit and CGS Unit, the additional weight units are

  1. Pound-force (lbf)
  2. Slug
  3. Gram

Question 5. Are the units of force and weight the same? Why?

Solution. Yes, since weight is considered a force in physics, the units of force and weight are the same. It is described as the force that pulls an object toward the surface of the earth by the gravitational field. Since a Newton (N) is a unit of force, a Newton (N) is a unit of weight as well.

Frequently Asked Questions

What is the SI unit of mass and weight?

Ans. The SI base unit of mass is the kilogram. The Newton is the weight measurement unit. It shares the same properties as force.

Is gram SI unit of weight?

Ans. The International System of Units (SI) uses the gram (originally gramme; SI unit symbol g) as the unit of mass that corresponds to one thousandth of a kilogram.

What is the unit of weight for 9th class?

Ans. Newton (N) is the SI unit of weight.

What is weight in class 9 physics?

Ans. It represents the amount of gravity acting on a body.

What is 1 newton?

Ans. The force needed to accelerate a mass of one kilogram at a rate of one meter per second squared in the absence of any other forces is one newton.

How is weight defined in the SI system?

Weight is defined as the force exerted on an object due to gravity.

How is the newton defined in the SI system?

The newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.

How does the newton relate to other units of force?

The newton is the standard unit of force in the SI system. It is equivalent to one kilogram-meter per second squared (kg m/s^2) or 0.2248 pound-force (lbf).

How is weight different from mass?

Mass is a measure of the amount of matter in an object, whereas weight is a measure of the force exerted on an object due to gravity. Mass is measured in kilograms (kg) in the SI system, while weight is measured in newtons (N).

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