Basic Definitions
Basic Definitions Mass It is quantity of matter contained in a body. It does not depend upon gravitational force. The fundamental unit of mass is the Kilogram (kg). Weight Weight is the force exerted by gravity. Weight of body is dependent upon gravitational force, so it is not constant. Weight = Mass x Gravitational acceleration W =m g Force It is push or pull acting on a body which changes or tends to change the state of rest or uniform motion of the body. As per Newton's second law of motion Force ∝ acceleration F= m a In SI unit (International system), unit of mass is kg and unit of acceleration is m/s2 and unit of the force is Newton (N). When m = 1 kg, and a = 1 m/s then F = 1 N. 1 N: When unit mass is given unit acceleration then the force produced is 1 N. Pressure It is the force exerted by fluid (liquid or gas) on unit area. It is a property of fluid. Pressure=Force/Area=N/m² The unit of pressure is known as Pascal (Pa) or N/m2 1 Pa = 1 N/m2 Other commonly used units