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In the previous sections, we have learned the acceleration due to gravity. In this section, we will discuss the basics of mass and weight and the differences between them.
Mass is the fundamental property of a body. The mass of a body is defined as the quantity of matter contained in the body.
The SI unit of mass is a \(kilogram\) (\(kg\)).
The gravitational force exerted on a body due to the earth's gravity alone is called the weight of a body.
Weight=GravitationalForce=mass(maccelerationduetogravity(g).g=AccelerationduetogravityoftheEarth(atsealevel) =9.8ms2.

Weight is a vector quantity. The direction of weight is always towards the centre of the earth. The SI unit of weight is \(Newton\) (\(N\)).
The weight of a body changes from one place to another on the earth's surface because it depends on the acceleration due to the gravity of the Earth (\(g\)). The weight of a body is higher at the poles than at the equatorial region.
The value of acceleration due to gravity on the moon's surface is \(1.625\) ms2. This is about \(0.1654\) times the acceleration due to the gravity of the earth.
If a person whose mass is \(50\ kg\) stands on earth's surface, his weight would be \(490 N\) (\(W\ =\ mg\ =\ 50 \times 9.8\)).
If the same person travels to the surface of the moon, he would weigh only \(81.25\ N\) (\(W\ =\ 50 \times 1.625\)). But, his mass remains the same (\(50\ kg\)) on both the earth and the moon.