Inertial and Gravitational Masses.

 Inertial mass : It is the mass of the material body, which measures its inertia.

If an external force F acts on a body of mass m_i, then according to Newton’s second law of motion

                F = m_ia or m_i = F/a

Hence inertial mass of a body may be measured as the ratio of the magnitude of the external force applied on it to the magnitude of acceleration produced in its motion.

 Gravitational Mass : It is the mass of the material body, which determines the gravitational pull acting upon it.

If M is the mass of the earth and R is the radius, then gravitational pull on a body of mass m_g is given by

                F = (GMm_g/R²) or m_g = (F/(GM/R²) = (F/E)

Here m_g is the gravitational mass of the body, if E = 1 then m_g = F

Thus the gravitational mass of a body is defined as the gravitational pull experienced by the body in a gravitational field of unit intensity.