Inertial Mass and Gravitational Mass

The mass of a body can be determined by measuring the acceleration 'a' produced in it by a known force 'F'.

Thus, the inertial mass can be determined.

Sub Topics

Gravitational mass
Equivalence of gravitational and inertial masses

Gravitational mass

The mass of a body can also be determined by the gravitational force exerted on it by the Earth.

Thus, gravitational mass can be determined.

Equivalence of gravitational and inertial masses

We know F = m_ia

Let us consider another body of inertial mass m_i^' and acceleration a^'. Let its gravitational mass be mg^|.

From (1) and (2),

For freely falling bodies, the acceleration due to gravity is the same, irrespective of the mass.

Newton performed experiments with a simple pendulum. He measured the time period of a hollow bob filled with different substances. He concluded from his observations that m_i = mg.

Hence, inertial and gravitational masses are equivalent.