It is the amount of matter contained in a given body, and does not vary with the change in its position on the earth’s surface. The mass of a body is measured by direct comparison with a standard mass by using a lever balance.
It is the amount of pull, which the earth exerts upon a given body. Since the pull varies with distance of the body from the centre of the earth, therefore the weight of the body will vary with its position on the earth’s surface (say latitude and elevation). It is thus obvious, that the weight is a force.
It is the total motion possessed by a body. Mathematically,
Momentum = Mass × Velocity
A force equal in magnitude but opposite in direction and collinear with the impressed force producing the acceleration, is known as inertia force