diffrentiate between mass and weight?

tudents of physics often confuse mass and weight of an object and many also feel that there is no difference between the two, while the fact is that there is a lot of difference between these two physical quantities.

Mass is the amount of matter present in a body and is an intrinsic property of the body. Mass of an object remains the same always at any place.

Weight on the other hand is the force which a given mass feels due to the gravity at its place. Weight is measured in units of Force like Newton (which is the SI unit of Force).

If your mass is 60 kgs then your weight is approximately 60 x 10 = 600 Newtons. This is because

Force = mass x acceleration (From Newton’s second Law)

Thus, weight = mass x acceleration due to gravity

If you go to moon your mass remains same, i.e 60 kgs, but your weight becomes less by 1/6 amount, since moon’s gravity is 1/6 that of earth.

Mass of a body is measured by balancing it equally with another known amount of mass. You keep known amount of masses like blocks of 1 kg, 2 kg etc on one side till both the sides balance and then add up the numbers on the known side of mass and thus calculate the unknown mass. This works because, when the masses are equal on both the sides of the balance the effect of gravity cancels out for both (i.e weight cancels out) and hence we can calculate the mass on one side of the balance if we know the mass on the other side of the balance.

Weight is measured using a scale which effectively measures the pull on the mass exerted by the gravity of the earth.

Scale is used to calculate the mass of an object

Spring Balance is used to calculate the weight of an object

Table 1: Differences between Mass and Weight

If an object is in freefall towards the attractor (like earth), even then it has weight, but it experiences weightlessness (like an astronaut in a spaceship around the earth) since it is obeying the force. Weight can be felt only when the body in question tends to oppose the force of gravity (like u and me sitting on the surface of the earth:-)

Remember that even though we are at rest due to the friction between our self and earth’s surface, our acceleration is not zero, it is still 9.8 m/s² as the earth is constantly pulling us down towards its center. But we are resisting that pull and feel the force as weight. This force is a result of the acceleration due to gravity of the earth which our body is constantly experiencing because of its mass.

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♦Mass is the quantity of matter contained in a body, while weight is the force by which the body is pulled to the earth's center.
♦Mass is an intrinsic property of a body, as it remains the same everywhere in the universe. Weight is variable due to change in the magnitude of the gravitational force applied by the earth.
♦Mass is denoted by "M" while Weight (W) = Mass (M) * Gravitational acceleration (g)
♦Mass can never be zero, for then the body will have no existence. Weight can be zero if there is no gravitational force acting on the body, like that in the space.
♦Mass is indestructible But weight can be increased when there is more gravitational impact and decreased when less gravitational impact.
♦Mass is measured by a common balance. Weight is measured by a spring balance.
♦Mass is scalar and has no direction dependency. Weight is vector and is directed towards the center of the earth.

Mass is the measure of the inertia of the body. It arises due the total atomic content of the body, namely the constituents of its atoms. Mass is the universal quantity of the matter which remains unaltered irrespective of the place wherever me measure it.

The SI unit of mass is 'kilogram' (Kg)

weight of a body is the gravitational force acting on it.

Mg

If a body of mass 'M' kg is kept somewhere and acceleration due to gravity at that place is 'g' then the gravitational force acting on the body will be F _g = Mg

This 'mg' is the weight of the body.

Weight has units of 'Kgf' or 'Newton'

-weight of a body changes with the change in the value of 'g'

-weight of the body is not the universal quantity.

Mass is measure of matter contained in a body.

Scientific definition: Mass is inertia contained in a body . It is the basic property of a body.

S.I unit of mass is Kg (kilograms).

Weight is the pull on a body due to earth’s gravity. It’s a force and its S.I unit is Newton or kgms^-2.

Weight is related to the mass as

Mass

The mass (m) of a body is the quantity of matter contained in it. It is a scalar quantity which has only magnitude but no direction. The mass of a body is constant and does not change from place to place and it cannot be zero.Mass is a fundamental quantity.

SI unit of mass - Kg

Weight

The weight (W) of a body is the force with which it is attracted towards the center of the earth. Weight is a vector quantity having magnitude as well as direction. The weight of a body is not constant , it changes from place to place . For Eg in interplanetary space g=0 (g=acceleration due to gravity) , thus W =0 (as W=mg).Weight is a derived quantity.

SI unit of Weight= newton (N)

Mass: Mass of a body is the amount of substance contained in the body. Mass is a fundamental quantity. The SI unit of mass is kilogram (kg). Mass of a body is always a constant quantity.

Weight: Weight of a body is the gravitational force exerted on it by the Earth. Weight is a derived quantity. It is the product of mass and acceleration due to gravity. It is measured in Newton (N). The weight of a body changes with the change in gravitational field in which it is placed

Mass: Mass of a body is the amount of substance contained in the body. Mass is a fundamental quantity. The SI unit of mass is kilogram (kg). Mass of a body is always a constant quantity.

Weight: Weight of a body is the gravitational force exerted on it by the Earth. Weight is a derived quantity. It is the product of mass and acceleration due to gravity. It is measured in Newton (N). The weight of a body changes with the change in gravitational field in which it is placed.

 Mass is independent of gravity and it tells us the amount of matter present in the object. It remains constant throughout the universe.

Weight tells us the force with which an object is attracted by the gravitational force, it depends upon gravity and varies from place to place in the universe.

For example our mass remains same whether we are on Earth or on Moon. But our weight on Moon will be different from our weight on the Earth.

 Mass and weight are two different terms. Mass is defined as the amount of matter present in a body while weight is the force exerted on a body by gravity.

1) Hence mass is independent of gravity while weight depends on gravity.

2) Mass of an object is constant everywhere whereas the weight of an object varies from place to place depending upon the gravity. For example our mass remains same whether we are on Earth or on Moon. But our weight on Moon will be different from our weight on the Earth as gravity is different.

3)The mass of an object is measured in Kilogram (SI unit) where as the weight is measured in Newtons. The expression for weight is W = m X g

where W is the weight, m is the mass of the body and g is the acceleration due to gravity.

 The amount of substance contained in an object is called mass while the force by which the Earth or other planet attracts the object is called weight. That is, weight is force due to gravity.

♦Mass is the quantity of matter contained in a body, while weight is the force by which the body is pulled to the earth's center.