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Gravity 1

Well, hello there! This is the intro bits to understanding gravitational forces.

Have you noticed how magnets attract each other. Amazing! And the closer you bring magnets to each other, the stronger the attraction. Well, this kind of attraction occurs not only for magnets.

ALL objects attract each other just because they have mass! No kidding.

An apple attracts an orange, but the attraction is so small that there is no visible effect. However, if the masses were very large, the attraction between the masses can become very noticeable indeed!

The force of attraction between objects as a result of their masses is called Gravitational Forces.

Objects m1 and m2 attract each other as a result of their masses. We say that there is a Gravitational Force of Attraction between the masses.

Gravitational forces are ALWAYS ATTRACTIVE.

Important

1. The SIZE of the gravitational FORCES between the masses is the SAME FOR BOTH. It does not matter that one object is larger than the other. Each object pulls the other equally hard. This is because of Newtons Third Law of Action and Reaction.

2. We loosely say that there is a gravitational force between the masses. Actually, there are TWO such forces, one per object. The forces are the same size, but act in opposite directions. We can show the TWO gravitational forces by a force vector diagram.

3. We can calculate the MAGNITUDE (size) of the forces from a simple equation.

F is the size of the force (the same F acts on each mass, in opp directions)

G is called the Gravitational Constant of Proportionality.

m1 and m2 are the masses

r is the distance between the centre of the masses (r is squared in the equation)

4. If the masses are brought closer to each other, the force becomes larger.
(If you move closer to a fire, you feel hotter!).
It is said that the Force is inversely proportional to the distance squared.
This can be mathematically represented as shown below.

Inverse Proportion (opposite effects) ::A smaller distance creates a larger force.

5. Gravitational forces exist for all masses anywhere in the universe. Gravitational forces range from being very small (so small that they cannot be detected) to very large. Even two protons attract each other due to their masses! However, their electrostatic repulsion force is far greater than their gravitational attraction force!