Gravity

Definition Gravity is a force of attraction between objects, that is due to the masses of the objects.

Law of Universal Gravitation This law mathematically describes the relationship between the strength of gravitational force between objects, the masses of objects and the distance between the objects. F= Gm1m2/r2

Law of Universal Gravitation Part 1: Gravitational force depends directly on the objects’ masses. The more mass objects have the greater the gravitational force between them. This explains why there is a large force on objects due to the Earth. The Earth has a huge mass.

Law of Universal Gravitation Part 2: Gravitational force depends inversely on the distance between the objects. The farther apart 2 objects are, the less the gravitational force between them.

Weight Weight is a measure of the gravitational force on an object.

Mass The amount of matter in an object. Gives information about how difficult it is to change an object’s motion. Is not affected by gravity.

Compare/Contrast Weight and Mass Amount of matter Force of gravity Affected by gravity Measured in grams or kilograms If mass increases, then weight increases as well. Measured with a spring scale Measured with a balance Measured in Newtons Same on the moon Different on the moon