Mass and Density

Abstract

Mass is a measure for inertia and heaviness of a body. Heaviness is caused by the Earth's gravitational attraction for a body. The force between the body of interest and the planet Earth is called the weight force of the body. Mathematically , this force can be expressed as the product of the body's mass and the Earth's acceleration due to gravity, as shown by equation (2.1). G = m · g (2.1) where G weight force in N m mass in kg g gravitational acceleration in m · s −2 Because the density of planet Earth varies with location and the planet is slightly pear-shaped and not in the shape of a perfect sphere, the value of gravitational acceleration differs slightly with location on the Earth's surface. Considering the rotation of the planet, a body resting at the equator will have a greater tangential speed and centrifugal force than in regions far north or south of the equator.