Mass and Weight - Definition, Relation, FAQs

When you lift a rice of bag, the bag feels heavy because of its weight, which is the force exerted by the gravity on it. However, the amount of rice in the bag, no matter where you are (Earth, Moon, or space), stays the same. This amount is its mass. But its weight changes on the moon. However, let's understand this concept in detail in the given article.

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This Story also Contains

1. What is Mass?
2. What is Weight?
3. Mathematical Relation Between Mass and Weight
4. Difference Between Mass and Weight

What is Mass?

Mass is defined as the amount of matter present in an object. It is a fundamental property that does not change regardless of the location in the universe. The greater the mass of an object, the more matter it possesses.

The S.I. Unit of mass is Kilogram (Kg).

Role in Physics: Mass is a fundamental property of matter and appears in Newton's Second Law of Motion and momentum, $F=m a$,

where,

• $F$ is force
• $m$ is mass
• $a$ is acceleration.

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Types of Mass

Mass can be categorized into two types:

1. Inertial Mass: Measures an object's resistance to acceleration when a force is applied.
2. Gravitational Mass: Determines the strength of the gravitational force exerted by or on the object.

What is Weight?

The force exerted on an object due to gravity is called the Weight of an object. It is a vector quantity meaning it has both magnitude and direction. It changes with the strength of the gravitational field. Unit of Weight is the newton (N), as it is a measure of force.

For example, an object weighs less on the Moon than on Earth because the Moon's gravity is weaker.

Formula to Calculate Weight

$$
W=m g
$$

where $W$ is weight, $m$ is mass, and $g$ is the acceleration due to gravity (approximately $9.8 \mathrm{~m} / \mathrm{s}^2$ on Earth).

Mathematical Relation Between Mass and Weight

The weight ( $W$ ) of an object is directly proportional to its mass $(m)$ and the acceleration due to gravity $(g)$. The formula is:

$$
W=m g
$$

where $W$ is weight, $m$ is mass, and $g$ is the acceleration due to gravity (approximately $9.8 \mathrm{~m} / \mathrm{s}^2$ on Earth).

Difference Between Mass and Weight

The below table shows the difference between the Mass and Weight along with their properties: