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Unit of Weight

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Last updated date: 27th May 2024
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An Introduction

We presume that when we buy a kg of onion, the '1 Kg' refers to its weight. However, according to the fundamental rules of physics, the combination of mass and acceleration equals weight. Basically, if we assume a 10 m/s acceleration, the mass will be 100 grams. So, did you buy 100 grams of onion or one kilogram of onion? The Unit of Weight is responsible for the entire logistics in connection to the relevance of the actual unit to represent the unit 1 kg. 

 

On the other hand, you often label an object as heavy if you are unable to lift it off the ground? But is that all there is to the term ‘weight’? Or is there much more to it? 

 

Also, how do we express weight mathematically? Do you use a unit of weight or mention the numerical value? Read on to find out more about it! 

 

What is Weight?

Merely speaking, the weight of an object is the force with which the gravitational field of the Earth pulls it towards the surface. In other words, weight refers to the force at which a body accelerates towards the surface of Earth because of its gravitational pull. 

 

As you know, anything suspended in air falls to the ground. The reason for this phenomenon is that this planet possesses a field of gravity which enables an object to fall on the ground. For instance, when you hold a ball or an egg higher from the ground level and let go of it from your hold. You witness that it immediately drops on the ground. 

 

Therefore, the SI unit of weight aims to express the numerical value of the force that attracts an object towards the ground. 


Understanding Weight

The force with which the gravitational field pulls an object towards the earth's surface is known as weight.


We're all aware that the center of gravity exerts a force that pulls all objects towards it. The numerical representation of how much force is required to force an object to reach the earth's surface is the unit of weight.


What is the SI unit of weight? 

Consider that an object whose mass is 1 kg falls vertically on the ground under a gravitational force of 1 m s-2. Now, if you are wondering what is the unit of weight, it is the product of all these components. 

 

Therefore, weight = mass X gravity. 

 

In this case, weight of the object is – 

 

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

 

Thus, the standard unit of weight is kg m s-2. However, you can also express it in terms of Newton (N). This very unit calls after the famed scientist Isaac Newton who first discovered gravitational pull. 

 

Therefore, Newton (N) refers to the SI unit of weight.

 

What are the Alternative Units of Weight?

  • Dimensional Unit of Weight – MLT-2, where M stands for mass, L refers to distance, and T is time. 

  • CGS Unit of Weight – Dyne. CGS unit implies centimeter-gram-second, where weight becomes 1 g cm s-2. You can also arrive at dyne when you divide 1 Newton by 10000. 

  • Base Unit of Weight – The base unit is the one that we have already discussed earlier. Therefore, it is kg m s-2

 

Metric Conversion of Units of Weight

One of the most universally accepted units of weight is gram. The conversion of a gram to kilogram is based on the standard denominations, as mentioned below:

1 g = 0.001 kg

1 mg = 0.000001 kg = 0.001 g

Further, 1 centigram = 0.00001 kg = 0.01 g

1 metric ton = 1000 kg

 

Solve the Following Problems by Yourself 

  • Object A has a mass of 5 kg. On the other hand, the gravity working on it is 10 m s-2. Find out what the standard unit of weight is in the case of object A. 

  •  The unit of weight in the SI system for an object X is 150 N. If the mass of object X is 50 kg, find out the gravitational pull working on it. 

  • The gravitational force on the surface of the moon is only 1/6 as strong as the gravitational force on the earth. What is the weight in Newtons of a 10 kg object on the moon and on the earth?


Understanding Mass

The mass of an object is defined as the amount of substance contained within it. Although mass and weight have separate meanings, they are sometimes misunderstood. The quantitative measurement of inertia is what it's termed.


The mass, unlike the weight, has a fixed value that is unaffected by gravitational changes. It can be represented as a kilogram or a gram. Thus, regardless of the presence or absence of gravitational pull, a body with a mass of 70 kg on Earth will have the same mass on the Moon.

 

Relation Between Mass and Weight

According to Newton's 2nd Law of Gravitation, force (F) equals the product of mass (M) and rate of acceleration (rate of acceleration) (A). 


F= MA


Even if the mass remains the same, the weight changes due to gravitational changes. As a result, a person's weight on Earth and on the Moon will differ significantly.


What is the Difference Between Weight and Mass? 

You might often come across people who use the terms ‘weight’ and ‘mass’ interchangeably. However, these two terms have fundamental differences in what they mean scientifically. In simple terms, mass refers to the amount of matter that an object possesses. 

 

On the other hand, weight implies the force with which the object travels towards the surface of earth. It suggests that weight differs for an object as per alterations in the gravitational pull. 

 

For instance, the mass of an astronaut remains the same on both earth and moon. Yet, the gravitational pull is 6 times lesser on the moon than on Earth. As a result, an astronaut will weigh 6 times less on the moon than on Earth. 

 

Now that you know what the unit of weight is, follow through the related topics to understand this concept even better. You can also download our Vedantu app to experience personalized learning online along with highly interactive sessions.

FAQs on Unit of Weight

1. What is weight?

Weight is the force with which the earth pulls an object towards itself due to its gravitational force. Also, the  objects which have the same mass in the same gravitational field, also have the same weight.

2. What is the SI Unit of weight?

SI unit of weight is Newton (N) which can be defined as kg m s-2.

3. What is the base unit of weight?

The base unit of weight is kg m s-2, where kg stands for kilogram, m denotes meter and s stands for seconds.

4. What are the other units of weight?

Other units of weight are:

  • Pound-force (lbf)

  • Slug

  • Gram

5. How to convert gram to kilogram as per the standard denominations?

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

6. What are the seven basic units of measurement?

The seven basic units of Measurement are: 

1. meter (m) for Distance

2. kilogram (kg) for Mass

3. Second (s) for time

4. Kelvin (K) for Temperature

5. Ampere (A) for Electric Current

6. Mole (mol) for Amount of substance

7. Candela (cd) for Luminous Intensity

7. What is the difference between mass and weight?

The differences between mass and weight are

Mass

Weight

1. The mass of an object is the amount of matter contained within it.

1. Weight refers to the force that pulls an object towards its center of gravity.

2. Because it has only magnitude but no direction, it is a scalar quantity.

2. Because it has both direction and magnitude, it is a vector quantity.

3. Regardless of gravitational forces, mass has the same value.

3. Gravitational changes affect the weight as the force increases or decreases.

4. Gravitational force fields have no impact on a body's mass, hence mass can never be zero. 

4. When there is no gravitational force, weight can be zero.

5. Mass is measured using beam balance, calibrated balance, or analytical balance.

5. Weight is measured using a spring balance or compression balance.

6. It is represented by Kilogram (Kg) or Gram (g).

6. It is represented by the term Newton (N).


We hope you found this article on units of weight helpful. If you have any doubts, let us know in the comments section below. We will be happy to help you.