Question

Differentiate between mass and weight.

Answer 1

Hint: Though mass and weight are closely linked, they are not the same. The weight of a body depends upon its mass directly. However, the mass of the body is not dependent upon its weight. The mass relates to the amount of matter in a body and is thus a characteristic property of the body.

Complete answer:
The mass of the body is the amount of matter contained in it. Thus, greater the amount of matter contained in a body, greater will be its mass. In the SI units, mass is measured in kilograms (Kg).
On the other hand, weight of a body is the force by which the earth pulls it towards its centre, that is, the gravitational force exerted by the earth on that object. Since it is a force, it is measured in Newton (N).

The weight of a body depends upon its mass since the force exerted by the earth depends upon the mass of the object. However, there is no such dependence of the mass of a body on its weight.
Since, the weight is a force and forces are vectors, the weight of a body is a vector quantity while the mass of a body is a scalar quantity since it has only magnitude and no direction.

The mass $M$ and the weight $W$ of a body are related by
$\overrightarrow{W}=M\overrightarrow{g}$
Where $\overrightarrow{g}$ is the acceleration due to gravity.

Note:
Students must note that in everyday life, the terms mass and weight are often used interchangeably. For example, we often say that weight of a person's weight is $40Kg$, when we are actually referring to his mass. However, the two terms are not the same in scientific terms as has been explained above.
Students must also note that the weight of a body can be zero (for example in zero gravity space where no force of gravity acts on the body), however the mass of a body being zero means that there is no matter inside the body and it does not exist and hence, is not possible.