Mass vs Weight : Comparing and Understanding the Differences

We often use the words mass and weight synonymously, but they have quite different meanings, especially in Physics. The difference between mass and weight is that your mass remains the same whereas your weight keeps changing no matter wherever you go in the universe. We will help you study the difference between mass and weight with examples. So, let’s dive right in!

Mass & weight

What is Mass?

Mass is a measurement of an object’s tendency to resist changing its state of motion, known as inertia. In simpler words, we can define mass as how much material an object consists of. In Physics, it is the basic property of matter and one of the fundamental quantities.

For example, think of a puck on an air hockey table. Unless some force, like banging into a wall, or friction, acts on the puck, it will keep sliding on the same path forever. Mass is a measure of how much force it will take to change that path.

Therefore, mass refers to both- the property of a physical body and the measure of the resistance of the object to acceleration when we apply a net force.

The SI unit of mass is Kilogram (Kg). There are various units of calculating mass, like, kilograms, grams, pounds, lbs, etc. Every unit can be converted to other units by using a proper conversion formula without affecting the meaning and essence of the quantity to be measured.

Mathematically, the formula of mass can be defined from Newton’s second law. If the acceleration (a) of a body is due to a force (F), then its mass (m) is given by :

m = F/a

What is Weight?

We can define weight as a measure of the amount of downwards force that gravity exerts on an object. This force increases with the object’s mass: the more inertia it has, the harder gravity pulls. On Earth’s surface, the force of gravity is about 9.8 newtons per kilogram.

The SI unit of weight is newtons. The formula of weight can be defined if mass (m) is multiplied by the acceleration of gravity (g),

w = m*g

Difference between Mass and Weight:

Here, the correlations and difference between mass and weight with examples are given in the tabular form below.

Sl. No.Differentiating PropertyMassWeight
1DefinitionWe can simply define mass as the amount of matter in a body.We can define weight as the amount of force acting on a mass due to acceleration due to gravity.
2DenotationMass is denoted by “M”.Weight is denoted by “W”.
3FormulaMass is always constant for a body and there are several formulas to calculate mass.One way to calculate mass is:Mass = volume × densityWeight is the measure of the gravitational force acting on a body.Weight can be calculated from the following formula:Weight = mass × acceleration due to gravity
4Quantity TypeMass is a base quantity.Mass only has magnitude and so, it is a scalar quantity.Weight is a derived quantity.Weight has both magnitude and direction (towards the centre of gravity) and so, it is a vector quantity.
5Unit of MeasurementThe SI unit of mass is Kilogram (Kg).The SI unit of weight is newtons (N).
6Gravitational EffectMass does not depend upon gravity and is constant everywhere.Mass can never be zero.Weight is dependent on gravity and so, it varies from place to place.Weight can be zero where there is no gravity (like space).
7Measuring InstrumentMass can be easily measured using any ordinary balance like lever balance, pan balance, beam balance, etc.Weight can be measured by a spring balance or by using its formula.

Difference between Mass and Weight is Mass is a measure of Inertia and Weight is a measure of Force. It’s simply because we are accustomed to managing conditions on the surface of Earth that we regularly use mass and weight synonymously. At the point, when we say somebody weighs 73 kilograms, we truly mean their mass – their weight would be 73 * 9.8 = 715.4 newtons. (This force – 715.4 newtons – is what washroom scales are estimating. They convert it into kilograms for comfort.)

The force of gravity is weaker on the surface of the moon (about 1.6 newtons per kilogram, or a sixth Earth’s gravity); a 73 kilos astronaut would weigh only 116.8 newtons.

So a trip to space might be a quickest way to lose weight, but losing mass is altogether a different story.

Key fact about Mass and weight:

Did you know that by measuring our weight, we actually measure our mass?

Our weight is not same on Moon and in the space. Gravity plays an important factor as the fact moon has lesser gravity when compared to earth therefore, our mass remains constant but the weight becomes zero.

This is because the mass of a body depends on the volume occupied by the body, the weight demonstrate the energy of that object with respect to the attraction that gravity exerts with another object (According to the law of gravitation). Weight on land is determined by the force with which the earth attracts us to the ground. We do not weigh the same at the top of a mountain as at sea level, so we use global standards to avoid mistakes since the difference is very small.

On the other hand, it is worth noting that our body in water weighs less due to the buoyancy exerted by a force contrary to the force of gravity.

With help of ICSE Class 7th Phyiscs Study material by Extramarks, you can clear your concepts for more topics like MagnetismElectricity etc.

Frequently Asked Questions (FAQs) on difference between mass and weight

  1. Give an example to explain the difference between Mass and Weight.

Mass is a quantity of matter in a body and it remains constant wherever you go. On the other hand, weight changes under the change of gravitational acceleration. For example, the weight of an object of mass 56 kg is 560N on the Earth. However, its weight on the Moon is 90N.

  1. What is the difference between mass and weight in terms of quantity type?

Mass is a scalar quantity and weight is a vector quantity.

  1. How do you calculate mass from weight?

To find an object’s mass using its weight, the formula is Mass (M) equals Weight (W) divided by the Acceleration of Gravity (G).

M = W ÷ G

  1. Can Mass be created?

In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system’s mass cannot change, so quantity can neither be added nor be removed.

  1. What instruments can we use to measure mass and weight?

A scale or balance is a device to measure weight or mass. These are also known as mass scales, weight scales, mass balances, and weight balances.