Acceleration, Weight and Mass

Weight Near the surface of the Earth, the pull of gravity on a body is practically constant and every falling body acquires constant acceleration equal to “g” The force that accelerates the body downward is equal to its weight “w”

It follows that if “m” is the mass of the body, then Newton’s 2 nd law equation, F = ma can be restated as: This enables us to compute the weight of a body from its mass, or the mass of the body from its weight.

“g” can also be calculated for another planet by the equation:

Gravitational v. Inertial Mass Obtaining a mass measurement based on the pull of gravity on a body is known as gravitational mass.

Is gravity needed to measure mass? If some known force is applied to a body, and its acceleration is measured, we can calculate the mass using Newton’s 2 nd law. Since the amount of mass is related to body’s inertia, an how much it resists a change in motion, it is called the inertial mass.