Ch 09 - GRAVITATION9th Science

Gravitation:
The universal macro-concept. It is the force of attraction that exists between any two objects anywhere in the universe (e.g., Sun and Earth).

Gravity:
A localized effect. It specifically refers to the force of attraction between the Earth (or another specific celestial body) and material objects on or near its surface.

Every object in the universe attracts every other object with a fundamental force. This force is:

1. Directly Proportional to the product of their masses ($M \times m$).
2. Inversely Proportional to the square of the distance between their centres ($d^2$).

Crucial Condition: The gravitational force acts strictly along the straight line joining the centres of the two objects.

Variables & Units:

• F = Gravitational force (N)
• G = Universal Gravitational Constant ($N \cdot m^2 \cdot kg^{-2}$)
• M, m = Masses of the two interacting objects (kg)
• d = Distance between the centres of the objects (m)

Conditions/Notes:

• This is an inverse-square law. If the distance $d$ is doubled, the gravitational force becomes $\frac{1}{4}th$ of its original value.