Unit of Weight - SI Unit, CGS Unit and Other Units, FAQs

Unit of Weight - SI Unit, CGS Unit and Other Units, FAQs

Vishal kumarUpdated on 02 Jul 2025, 05:01 PM IST

In this article, we will talk about the unit of the weight, the SI unit of the weight, the standard unit of weight, cgs unit of weight and the specific weight units.

This Story also Contains

  1. What is the SI unit of weight?
  2. SI Unit of Mass
  3. What is unit weight?(or Specific weight)
  4. Specific weight units
  5. What is the basic unit of weight?
  6. Difference between the SI Units Of Mass and weight.
  7. ALL units of weight
Unit of Weight - SI Unit, CGS Unit and Other Units, FAQs
Unit of Weight

the SI unit of weight(or the standard unit of weight) is Newton

When we talk about the unit of weight, it sounds confusing. The reason is because weight is measured in terms of force, i.e, Newton whereas the standard unit of mass is Kilograms. We link both weight and mass with each other. However, they are scientifically two different quantities. Similarly, we often get confused about the unit of weight. Now, let’s discuss the difference between weight and mass and also we will discuss the unit of weight and mass.

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What is the SI unit of weight?

SI Unit of weight is Newton(or we can say that the Standard unit of weight is Newton)

We have different weight measurement units but still we study the SI unit of weight because SI units are standard units and are acceptable globally. It is a fixed and uniform way of measuring any physical quantity. Therefore, the SI Unit of weight is Newton or we can say that the Standard unit of weight is Newton. We define newton as “It is the necessary force that is provided to a mass of one kilogram with an acceleration of one metre per square second .”

As we know that the SI unit of weight is Newton. Newton is a derived unit and it can also be expressed in SI base units as kg⋅m/s2

 The SI Unit of weight is Newton.  We define newton as “It is that force necessary to provide a mass of one kilogram with an acceleration of one metre per second per second.”

Formula of weight : We can calculate the SI unit of weight or the Standard unit weight using the formula given below.

W = F =m g

Where, W = weight[What is the symbol for weight?]

F = Force(net force/external force)

m = mass

g = acceleration of gravity

m = W ÷ g [convert weight to mass]

FORMULA FOR UNIT OF WEIGHT

1 N = 1 kg ms2

Hence, it tells that the SI unit of weight(or the standard unit of weight) i.e, is we require 1N force to move a body of mass 1 kilograms by an acceleration of 1 metre per second square.

The table includes the different weight measurement units such as the SI unit of weight, CGS unit of weight, and the dimension of weight:

SI unit of weight

N

SI base unit of weight

kg.m.s-2

CGS UNIT OF WEIGHT

dyne

DIMENSION OF WEIGHT

MLT-2

CGS Unit of Weight – Dyne. CGS unit implies cm-g-s, where the weight becomes 1 g cm s-2. We can also calculate dyne by dividing 1 N by 10000.

Other Unit of Weight

Other units of weight known to us are pound-force (lbf), slug, gram, amongst others.

Conversion of The Units Of Weight

1 g = 0.001 kg

1 mg = 1.010-6 kg = 1.010-3 g

1 centigram = 1.010-5 kg = 1.01023 g

1 metric ton = 1.0103 kg[1 unit to ton]

1u=1.6605402E-27 kg[1 unit kg]

Commonly Asked Questions

Q: What is the SI unit of weight?
A:
The SI unit of weight is the Newton (N). Weight is a force, and in the International System of Units (SI), force is measured in Newtons. One Newton is defined as the force required to accelerate a mass of 1 kilogram at a rate of 1 meter per second squared.
Q: How does the unit of weight relate to the concept of impulse?
A:
Impulse is the product of force and time. Since weight is a force, it can contribute to impulse. The unit of impulse is Newton-seconds (N·s), which combines the unit of weight (N) with time. This relationship is important in understanding changes in momentum due to gravitational forces.
Q: How does weight affect the concept of terminal velocity?
A:
Terminal velocity is the constant speed achieved by an object falling through a fluid when the drag force equals the gravitational force (weight). Heavier objects generally have higher terminal velocities in the same fluid because the drag force must increase to balance the greater weight.
Q: What is meant by "weight fraction" in chemistry and materials science?
A:
Weight fraction is the ratio of the weight of a particular component to the total weight of a mixture or compound. It's often used in chemistry and materials science to describe composition. Unlike mass fraction, weight fraction can vary slightly with location due to changes in gravitational field strength.
Q: How does weight relate to the concept of pressure in hydraulic systems?
A:
In hydraulic systems, the weight of the fluid contributes to the pressure within the system. According to Pascal's principle, pressure applied to an enclosed fluid is transmitted equally in all directions. The weight of the fluid itself creates a baseline pressure that increases with depth, which is crucial in designing and operating hydraulic systems.

SI Unit of Mass

The SI unit of mass is kilograms.[Don’t get confuse it with the SI unit of weight or the standard unit of weight i.e, Newton]

As we know that the standard unit of weight is Newton. But there are many different units systems. Such as the specific weight units and the basic weights.

SI UNIT OF MASS is kg

Commonly Asked Questions

Q: Why do bathroom scales show kilograms instead of Newtons?
A:
Most bathroom scales are calibrated to show mass in kilograms rather than weight in Newtons for convenience. They assume standard Earth gravity to convert the measured force (weight) into an equivalent mass. This works well on Earth but would be inaccurate in locations with different gravitational strengths.
Q: How is weight measured in space?
A:
In space, where objects are often in free fall (weightless), mass is typically measured instead of weight. This is done using devices that measure the inertia of an object, such as the Space Linear Acceleration Mass Measurement Device (SLAMMD) used on the International Space Station.
Q: Why don't we just use mass instead of weight in everyday life?
A:
In everyday life on Earth, weight is often more practical because it's what we directly experience and measure (e.g., on scales). Since the gravitational acceleration is nearly constant on Earth's surface, weight is proportional to mass, making it a convenient proxy for mass in most terrestrial situations.
Q: Why is weight considered a vector quantity?
A:
Weight is a vector quantity because it has both magnitude and direction. The magnitude is determined by the mass and the strength of the gravitational field, while the direction is always towards the center of the gravitating body (typically downward on Earth's surface).
Q: How does weight affect the concept of "weightlessness" in orbit?
A:
Objects in orbit are not actually weightless; they still have weight due to Earth's gravity. However, they experience apparent weightlessness because they are in a constant state of free fall around the Earth. The orbital path curves at the same rate the object falls, creating the sensation of weightlessness.

What is unit weight?(or Specific weight)

The specific weight is also known as the unit weight.

Specific weight is the weight per unit volume of any material.

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Commonly Asked Questions

Q: What is specific weight?
A:
Specific weight is the weight per unit volume of a substance. It's calculated by multiplying the density of the substance by the acceleration due to gravity. The SI unit for specific weight is N/m³ (Newtons per cubic meter).
Q: What is meant by "weight per unit length" in materials science?
A:
"Weight per unit length" is often used in materials science and engineering to describe linear density. It's typically expressed in units like N/m (Newtons per meter) and is useful for characterizing materials like wires, ropes, or beams where the cross-sectional properties are consistent along the length.
Q: How does weight relate to the concept of "g-force"?
A:
G-force is a measure of acceleration relative to freefall. One "g" is equal to the acceleration due to Earth's gravity at sea level (about 9.8 m/s²). When experiencing higher g-forces, objects feel heavier because the apparent weight increases proportionally to the g-force.
Q: Can weight be negative?
A:
In physics calculations, weight can be considered negative when it acts in the opposite direction to the chosen coordinate system. However, in practical terms, weight is always a downward force due to gravity and is typically considered positive in magnitude.
Q: What is the difference between static weight and dynamic weight?
A:
Static weight is the weight of an object at rest, while dynamic weight refers to the apparent weight of an object in motion or under acceleration. Dynamic weight can be different from static weight due to inertial forces, which is important in designing structures subject to motion or vibration.

Specific weight units

We commonly use a value of the unit weight of water. And value on Earth at 4 °C is 9.807 kN per metre cube.It is also known as specific weight for water.

The terms specific weight(or specific density) is also used to measure relative density. Gamma(γ), commonly known as a specific weight symbol.

We define specific weight or the unit weight (γ) of a material as the product of its density ρ and the gravity(standard) g:

γ = ρ g[THE UNIT WEIGHT FORMULA]

Unit of density = kg/m3

cgs unit of density= g/cm^3

gravity(standard)= m/s2

cgs unit of g = cm/s^2

Commonly Asked Questions

Q: How does the unit of weight relate to pressure?
A:
Pressure is defined as force per unit area. Since weight is a force, it's often used in pressure calculations. For example, the pressure at the bottom of a column of fluid is calculated using the weight of the fluid above it divided by the area.
Q: What is the weight of 1 liter of water on Earth?
A:
One liter of water has a mass of approximately 1 kg. On Earth, this translates to a weight of about 9.8 N (Newtons). This relationship (1 liter of water weighing about 9.8 N) is often used as a convenient reference in practical applications.
Q: How does the unit of weight relate to energy units?
A:
The unit of weight (Newton) is related to energy units through work. Work is force multiplied by distance, so lifting a weight (applying a force) over a distance produces work, measured in Joules (N·m). This connection is crucial in understanding potential energy in gravitational fields.
Q: What's the difference between weight and gravitational force?
A:
Weight is actually the gravitational force acting on an object. The terms are often used interchangeably, but "weight" specifically refers to the gravitational force experienced by an object in a particular gravitational field.
Q: How does buoyancy affect measured weight?
A:
Buoyancy reduces the apparent weight of an object immersed in a fluid. The buoyant force is equal to the weight of the fluid displaced by the object, as stated by Archimedes' principle. This is why objects seem lighter or even float in water.

What is the basic unit of weight?

Pounds(lb) is the basic unit of weight.

Difference between the SI Units Of Mass and weight.

The SI unit of mass and weight are as follows:

The SI Unit of mass or the MKS unit of mass is Kilograms & the SI Unit of weight is Newton

(1 N = 1 kg ms2)

cgs units of mass and weight:

cgs unit of mass is grams and cgs unit of weight is dyne.

Commonly Asked Questions

Q: How is weight different from mass?
A:
Weight is the force exerted on an object due to gravity, while mass is the amount of matter in an object. Mass is constant regardless of location, but weight can change depending on the strength of the gravitational field. Mass is measured in kilograms (kg), while weight is measured in Newtons (N).
Q: What is the relationship between weight and mass on Earth?
A:
On Earth, weight (W) is related to mass (m) by the equation W = mg, where g is the acceleration due to gravity (approximately 9.8 m/s² on Earth's surface). This means that an object with a mass of 1 kg will have a weight of about 9.8 N on Earth's surface.
Q: Would an object's weight be the same on the Moon as on Earth?
A:
No, an object's weight would be different on the Moon. The Moon's gravitational field is weaker than Earth's, about 1/6 as strong. So, an object would weigh about 1/6 of its Earth weight on the Moon, even though its mass remains the same.
Q: Can weight ever be zero?
A:
Yes, weight can be zero in a state of free fall or in the absence of a gravitational field. Astronauts in orbit experience weightlessness because they are in a constant state of free fall around the Earth, even though they are still affected by Earth's gravity.
Q: What's the difference between weight and apparent weight?
A:
Weight is the actual force due to gravity, while apparent weight is the force an object seems to exert in certain situations. For example, in an accelerating elevator, your apparent weight may feel greater or less than your actual weight due to the additional forces involved.

ALL units of weight

  • The SI Unit of weight/ standard unit of weight is Newton or we can say that the weight is measured in Newton.

  • The cgs unit of weight is dyne.

  • The base unit of weight is kg.m.s-2

  • The basic unit of weight is pounds(lb)

  • unit of unit weight is N

  • Common units of weight are kg, g, mg, etc.

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Hence, we conclude that the standard unit of measuring weight in India and all over the world is Newton(N). The unit of weight in SI system is Newton everywhere. Also, the standard unit for measuring weight is Newton as well.

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NCERT Physics Notes:

Commonly Asked Questions

Q: Why do we use different units for weight in different systems?
A:
Different unit systems were developed in various regions and for different purposes. The SI system (using Newtons) is internationally standardized, while others like CGS (using dynes) or the imperial system (using pounds) are still used in specific contexts or regions due to historical reasons or practical applications.
Q: What is the CGS unit of weight?
A:
In the CGS (centimeter-gram-second) system, the unit of weight is the dyne. One dyne is defined as the force required to accelerate a mass of 1 gram at a rate of 1 centimeter per second squared.
Q: How does a Newton compare to a dyne?
A:
One Newton is equal to 100,000 dynes. This large difference is due to the different base units used in the SI and CGS systems. The SI system uses larger base units (meters, kilograms) compared to the CGS system (centimeters, grams).
Q: What is the imperial unit of weight?
A:
In the imperial system, weight is typically measured in pounds (lb). One pound is approximately equal to 4.45 Newtons.
Q: How does weight change with altitude?
A:
Weight decreases with increasing altitude because the strength of Earth's gravitational field decreases as you move away from the Earth's center. This change is subtle near Earth's surface but becomes more significant at higher altitudes or in space.

Frequently Asked Questions (FAQs)

Q: What is the significance of the weight-to-power ratio in engineering?
A:
The weight-to-power ratio is an important metric in various engineering fields, particularly in transportation. It's calculated by dividing the weight of a vehicle or machine by its power output. A lower ratio generally indicates better performance, as it means more power is available to move a given weight.
Q: How does weight affect the concept of buoyancy in different fluids?
A:
Buoyancy depends on the weight of the fluid displaced by an object. In fluids of different densities, the same object will experience different buoyant forces. For example, an object may sink in water but float in a denser fluid like mercury, even though the object's weight remains constant.
Q: What is the relationship between weight and inertia?
A:
While weight and inertia are related through mass, they are distinct concepts. Weight is the gravitational force on an object, while inertia is the object's resistance to changes in its state of motion. On Earth, we often use weight as a proxy for inertia because they're proportional, but this relationship doesn't hold in environments with different gravitational strengths.
Q: How does the concept of weight apply in astrophysics, particularly in the study of stars and planets?
A:
In astrophysics, the concept of weight is extended to the gravitational forces between celestial bodies. The weight of stellar material plays a crucial role in stellar structure and evolution. For planets, understanding their internal weight distribution is key to studying their composition, internal structure, and geological processes.
Q: What is meant by "specific weight capacity" in battery technology?
A:
Specific weight capacity in battery technology refers to the amount of energy a battery can store per unit of its weight, typically expressed in watt-hours per kilogram (Wh/kg). This metric is crucial in applications where the weight of the power source is a critical factor, such as in electric vehicles or portable electronics.
Q: What is the relationship between weight and the bending of light in general relativity?
A:
In Einstein's theory of general relativity, gravity is described as the curvature of spacetime caused by the presence of mass and energy. While weight is a classical concept, the mass that gives rise to weight also causes this curvature. This leads to phenomena like gravitational lensing, where the path of light is bent by massive objects, effectively linking the classical concept of weight to the behavior of light in curved spacetime.
Q: What is the significance of the weight distribution in structural engineering?
A:
Weight distribution is crucial in structural engineering as it affects the stability, stress distribution, and load-bearing capacity of structures. Uneven weight distribution can lead to imbalances, increased stress in certain areas, and potential structural failures. Engineers must carefully consider weight distribution in designing buildings, bridges, and other structures.
Q: What is meant by "reduced weight" in physics problems?
A:
"Reduced weight" typically refers to the apparent reduction in weight when an object is partially or fully submerged in a fluid. It's the difference between the object's true weight and the buoyant force exerted by the fluid. This concept is important in problems involving floating or submerged objects.
Q: How does the concept of weight apply in fluid dynamics?
A:
In fluid dynamics, the weight of fluids plays a crucial role in phenomena like hydrostatic pressure, buoyancy, and fluid flow. The weight of a column of fluid creates pressure, and differences in fluid weight (due to density variations) can drive convection currents.
Q: How does weight affect the period of a pendulum?
A:
Interestingly, the weight of a pendulum bob does not affect its period. The period depends on the length of the pendulum and the local gravitational field strength, but not on the mass or weight of the bob. This counterintuitive fact is often a source of confusion for students.