Sci. 1-4

Gravity: A force of Attraction

Pages 21-25

A. Gravity- the force of attraction between objects due to their masses.

B. The gravitational force pulls objects toward each other.

C. The reason that objects aren’t moving toward each other all the time is because the mass of the objects are too small to cause an attraction large enough to move the objects toward each other.

D. Earth’s gravity is very large so you must apply force to overcome Earth’s gravitational force anytime that you lift objects.

E. The Law of Universal Gravitation- (Sir Isaac Newton)- All objects in the universe attract each other through gravitational force.

1) Gravitational force is small between objects with small masses

2) Gravitational force is larger between objects with larger masses

3) If the distance between two objects is increased, the gravitational force is reduced.

F.Weight is a measure of the gravitational force exerted on an object. Weight changes as gravity changes.

G. Mass- the amount of matter in an object. Mass does not change. Weight on the moon is 1/6 of Earth’s. The mass is the same.