Ch 4 Gravitation HW and Notes



Gravitational force is attraction between any two masses. They do not have to be in contact as gravitational force acts over distances large and small.
The gravity we feel on earth is the mutual attraction between our own mass and the mass of the earth.

Universal gravitationis the relationship between two masses the distance that separates them.
400px-NewtonsLawOfUniversalGravitation.svg-300x210.png

Forces are equal in magnitude but opposite in direction as shown in the figure above. Think about it this way... Your weight is the force of attraction of the Earth's mass ON your mass, BUT your mass has the SAME amount of force of attraction ON the Earth too! Equal and opposite force vectors!

The magnitude of the gravitational force depends on the masses and the distance separating them.
The farther apart they are, the weaker the force of attraction and it varies as an inverse square function.

Relationship graphic from the Physics Classroom:
physicsClassroomUnivGrav.gif