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Understanding the Relationship Between Kilograms and Newtons

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What Is the Difference Between kgf and Newton?

In physics, understanding the relation between kg and newton is fundamental for solving problems related to force, mass, and weight. While the kilogram (kg) is used to measure mass, the newton (N) is the unit for force. Knowing their connection helps in accurately converting mass into force and vice versa—an essential skill for students and for anyone dealing with real-world physics scenarios.


What is the Relation Between Kg And Newton?

The relationship between kilogram and newton is based on Newton’s Second Law of Motion, which states that force equals mass multiplied by acceleration (F = m × a). On Earth, the standard acceleration is due to gravity, which is approximately 9.8 m/s2. This means that a mass of 1 kg experiences a force of about 9.8 N when placed under Earth's gravity. In other words, the relation between kg and newton formula is:


  • Force (N) = Mass (kg) × Acceleration (m/s2)
  • Weight (N) = Mass (kg) × 9.8 (m/s2)

This simple equation allows you to convert between kilograms and newtons whenever you need to determine the force or weight on Earth’s surface. For example, to find the force acting on a 5 kg object, multiply 5 kg by 9.8 m/s2 to get 49 N.


Detailed Comparison: Mass vs. Force vs. Weight

It is crucial to distinguish between mass, force, and weight to prevent confusion:


Physical QuantitySI UnitFormula / Definition
MassKilogram (kg)Amount of matter
ForceNewton (N)F = m × a
WeightNewton (N)W = m × g (g ≈ 9.8 m/s2)

While kilogram is a measure of mass, the newton specifically measures both force and weight.


Converting Kilograms to Newtons: Steps & Examples

Step-by-Step Conversion

To convert a mass in kilograms to its equivalent force or weight in newtons, follow these steps:


  1. Write down the given mass in kilograms (kg).
  2. Multiply the mass by 9.8 (the approximate value of g in m/s2).
  3. State the answer in newtons (N).

Example calculations:


  • 1 kg × 9.8 m/s2 = 9.8 N
  • 5 kg × 9.8 m/s2 = 49 N
  • 10 kg × 9.8 m/s2 = 98 N

This method applies not just to whole numbers but to any mass. If you want to convert 1000 kg to newtons, simply calculate 1000 × 9.8 = 9800 N.


Kg and Newton: Key Concepts and Formulas

Mass is a scalar quantity indicating how much matter an object contains, and it stays the same regardless of location. Weight, measured in newtons, is a force and changes with the local gravitational field.


  • 1 newton is defined as the force needed to accelerate 1 kg of mass by 1 m/s2 (1 N = 1 kg × 1 m/s2).
  • For estimation, 1 kg is often rounded up to 10 N, but the precise value is 9.8 N.
  • To convert newton to kilogram (finding mass from force), use: kg = N / 9.8.
  • For relationships with other units: 1,000 g (grams) = 1 kg; 1 N = 102 grams approximately.

Relation Between Kgf And Newton

The relation of kgf and newton is important for understanding older and non-SI force units. Kilogram-force (kgf) is defined as the force exerted by a mass of 1 kg under standard gravity (9.8 m/s2):


  • 1 kgf = 9.8 N
  • Kgf is a non-SI unit, while newton is the standard SI force unit.

If asked for the difference between kgf and newton, recall: kgf relates directly to Earth’s gravity, while the newton applies anywhere and is based on force per mass per acceleration.


Comparison Table: Kg, Kgf, Newton


ParameterKilogram (kg)Kilogram-Force (kgf)Newton (N)
Physical QuantityMassForceForce
SI Unit?YesNoYes
DefinitionAmount of matterForce of 1 kg under gravityForce to move 1 kg by 1 m/s2
Relation1 kgf = 9.8 N1 N = 1 kg × 1 m/s2

This table highlights the distinctions and the key conversion factors to remember for any competitive exam or physics calculation.


Quick Reference: Conversion Examples

Given Mass (kg)CalculationWeight (N)
11 × 9.89.8 N
55 × 9.849 N
1010 × 9.898 N

By using this approach, you can easily convert 10 newton to kg or any other values as required, supporting clear understanding of physics concepts.


Common Questions on Relation Between Kg And Newton

  • Is 1 kg equal to 10 newtons?
    Not exactly; 1 kg = 9.8 N (but 10 N is often used for quick estimations).
  • How to convert newtons to kilograms?
    Divide the force in newtons by 9.8 to get mass in kg (kg = N / 9.8).
  • What is the relationship between grams and newtons?
    1,000 g (grams) = 1 kg = 9.8 N, so 1 gram ≈ 0.0098 N.
  • When do I use 9.8 or 10 in calculations?
    Use 10 for rough estimation; use 9.8 m/s2 for accuracy, especially in exams.
  • What is the relation between kg and newton for class 9?
    The concept is the same: 1 kg mass exerts 9.8 N force under Earth's gravity.

For more about unit conversions and foundational physics, you can explore conversion of units and unit of force on Vedantu.


Why Understanding the Relation Between Kg and Newton Matters

Grasping the precise relation between kilograms and newtons is key for solving questions involving force, motion, and acceleration—central themes from Newton’s Laws of Motion and beyond. Using the correct formula ensures accuracy in exams and practical scenarios, including engineering, science, and day-to-day physics applications. This fundamental relationship not only boosts confidence but also sets a solid foundation for tackling more complex physics problems.


In summary, the relation between kg and newton is governed by Newton’s Second Law: 1 kg mass under Earth’s gravity produces a force of 9.8 N. Remembering this, along with related units like kgf and the distinction between mass and weight, is essential for mastering both academic and real-life physics.


FAQs on Understanding the Relationship Between Kilograms and Newtons

1. What is the relation between kg and Newton?

The relation between kg and Newton is defined by Newton's second law of motion, where 1 kilogram (kg) of mass exerts a force of 9.8 Newton (N) due to gravity.

- 1 kg = 9.8 N (on Earth at standard gravity)
- Newton (N) is the unit of force, and kilogram (kg) is the unit of mass.
- The formula connecting them: Force (N) = Mass (kg) × Acceleration due to gravity (9.8 m/s²)
- This relationship is crucial in physics and is directly aligned with the CBSE syllabus.

2. How do you convert kilograms to Newtons?

To convert kilograms to Newtons, multiply the given mass by the acceleration due to gravity (9.8 m/s²).

Steps for conversion:
- Use the formula: Force (N) = Mass (kg) × 9.8 m/s²
- Example: For 5 kg, Force = 5 × 9.8 = 49 N
- Remember, this conversion is valid at Earth's surface (standard gravity).

3. Is 1 kg equal to 10 Newton?

1 kg of mass is approximately equal to 9.8 Newton (N) of force, but for simple calculations, it is often rounded as 10 N.

- Standard value: 1 kg = 9.8 N
- For estimation: 1 kg ≈ 10 N

4. Why is 1 Newton equal to 1 kg m/s²?

1 Newton is defined as the force needed to accelerate 1 kilogram of mass by 1 meter per second squared.

This relation is based on Newton's second law (F = ma):
- 1 N = 1 kg × 1 m/s²
- Newton (N) is the SI unit of force.

5. How do you define 1 Newton?

1 Newton is the force required to give a 1 kg mass an acceleration of 1 m/s².

Definition details:
- 1 N = 1 kg × 1 m/s²
- It is the SI unit for measuring force.
- Common in physics problems (class 9, physics syllabus).

6. What are the differences between kilogram and Newton?

Kilogram is a unit of mass, whereas Newton is a unit of force.

Main differences:
- Kilogram (kg): SI unit of mass
- Newton (N): SI unit of force
- 1 kg measures how much matter; 1 N measures the push or pull acting on an object.

7. If an object has a mass of 2 kg, what is its weight in Newtons?

The weight of a 2 kg object on Earth is calculated as 2 × 9.8 = 19.6 N.

Calculation:
- Weight (N) = Mass (kg) × 9.8 m/s²
- For 2 kg: Weight = 19.6 N

8. Why do we use Newton as the SI unit of force?

Newton is used as the SI unit of force to standardize measurements in science and adhere to international conventions.

Reasons:
- Named after Sir Isaac Newton (discoverer of the laws of motion)
- Universal use makes scientific communication easier
- Directly relates mass and acceleration (F = ma)

9. Does the value of Newton change on the Moon or other planets?

The value of 1 Newton as a unit does not change, but the weight (force) exerted by a given mass varies with gravity.

- On the Moon, gravity is lower, so 1 kg = 1.62 N (approx)
- On Earth, 1 kg = 9.8 N
- The unit remains the same, but the force value changes with location.

10. What does 1 kgf mean and how is it related to Newton?

1 kgf (kilogram-force) is the force exerted by gravity on a 1 kg mass, which equals 9.8 Newtons.

- 1 kgf = 9.8 N (on Earth)
- kgf is sometimes used for convenience in calculations, especially in older textbooks.
- SI prefers using Newton for force.

11. What is acceleration due to gravity and its standard value?

Acceleration due to gravity is the rate at which objects accelerate towards Earth, and its standard value is 9.8 m/s².

- Symbol: g
- Standard value on Earth: 9.8 m/s²
- Used in calculating weight: Weight = Mass × g