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Weight of an Object on the Moon

Weight of an object on the moon is the force with which the object is attracted by the moon. The mass of the moon is less than that of the earth. So the force exerted by the moon on an object is also less. 

Let the mass of the object be 'm'. Let its weight on the moon be 'Wm'. By the universal law of gravitation, its weight on moon will be

= 2.431 x 1010 x G x m

Celestial Body Mass (kg) Radius (m)
Earth 5.98 x 1024 6.37 x 106
Moon 7.36 x 1022 1.74 x 106

Its weight on the earth will be

We = G x mM / R2, where, M is the mass of the earth, and R its radius.
= 1.474 x 1011 x G x m

Dividing the two weights Wm / We , we get

= 1 / 6



The value of g on the moon is only about one-sixth of that on the earth. So a body weighs one sixth on the moon than on the earth, though its mass is the same on the moon as on the earth. Weight, being a force, is measured in force units. In the S.I. system, the unit of weight is newton (N) and that of mass is kg. Weight is a vector quantity, mass is a scalar quantity.

The Kilogram Weight 

The weight of a mass of 1 kg on the earth is called a kilogram weight (symbol kg wt).

         1 kg wt = mg 
                    = 1 kg x 9.8 ms-2
                    = 9.8 N

Thus   1 kg wt = 9.8 N

Another term generally used for kg wt is kilogram force (symbol kg f).

Also 1 N = 1 kg wt/9.8 ~ 1/10 kg wt (approximately)
  ~ 100 g wt

Thus 1 N is the force with which a body of mass 100 g is attracted towards the earth. 


Mass and Weight

S. No




Mass is the amount of matter present in a body.

Weight is the gravitational force acting on a body.


Mass is a fundamental quantity.

Weight is a derived quantity.


Unit of mass is kg in S.I. system of units.

Unit of weight is kg. Wt or Newton in S.I. system of units.


It is measured by using a beam balance.

It is measured by using a spring balance.


It is a scalar quantity.

It is a vector quantity.


Its value remains the same.

Its value changes from place to place depending on the gravitational pull.


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