Mass is the amount of matter contained in a body. Mass of a body is the measure of inertia. Mass is a scalar quantity. Its unit is kg in SI system and gram in C.G.S. system. Mass of a body does not vary with position and remains the same everywhere. It is measured by a beam balance.
It is the force acting on a body due to gravity.
Weight = mass × acceleration due to gravity
W = mg
Weight is a vector quantity. S.I. unit of weight is newton or kgwt Weight varies from place to place. Weight of a body is maximum at the poles and minimum at the equator (∵ g is minimum at the equator and maximum at the poles).
Since gravitational force decreases with height, the weight of a body is less on the top of a mountain compared to that at the sea level. Weight of a body is measured by a spring balance. The dimensional formula of weight = [ M1 L1 T-2 ]
A a coconut of mass 1 kg falls from a tree. find its weight (Take acceleration due to gravity = 9.8 m s-2)
Mass = 1 kg
∴ weight = 1 kg × 9.8 m s-2 = 9.8 N
Difference between Mass and Weight
|It is the measure of matter contained in body.||It is the force with which a body is attracted towards the centre of the earth.|
|It magnitude does not change from place to place.||It changes with change in acceleration due to to gravity.|
|It is measured with the help of a physical balance.||It is measured with the help of a spring balance.|
|It is a scalar quantity.||It is a vector quantity.|
|It is measured in units of gram or kilogram.||It is measured in units of dyne or newton.|