Orbital Motion & Satellites — A/L Physics

A. Earth's Gravitational Field Intensity Definition: The gravitational field intensity at a point on or outside the Earth is the gravitational force per unit mass at that point, given by g = GM/r² where r is the distance from the centre of the Earth. Explanation: Earth's gravitational field intensity describes how strongly Earth pulls objects toward its centre. It depends on Earth's mass (M), the gravitational constant (G), and the distance from Earth's centre (r). At Earth's surface, this equals the familiar acceleration due to gravity (9.8 m/s²). As you move away from Earth, the field intensity decreases according to the inverse square law. This concept connects the abstract gravitational field theory to practical measurements we make on Earth. Think of it as: Imagine Earth's gravity as a magnetic field spreading outward from the centre. The strength of this 'magnetic pull' weakens as you move away, just like how a light bulb's brightness decreases with distance.