# Gravity: A Force of Attraction

## The Effects of Gravity on Matter

All matter has mass! Gravity is a result of mass. Compared to all other objects the Earth has the biggest mass (so a HUGE mass). Earth's gravitational force pulls everything toward the center of the earth. Because of the big force books, tables, and chairs in the room stay in place, and all dropped objects fall to the ground (Earth) rather than moving together or toward you.

## Newton and Study of Gravity

Unbalanced forces are needed to change the movement of objects. Newton summarized his ideas about gravity in a law that is now known as the law of gravitation.

## The Law of Universal Gravitation

Part 1: Gravitational force increases as mass increases

Part 2: Gravitational force decreases as distance increases

## Weight as a Measure of Gravitational Force

Weight is related to mass but they are not the same. Mass is the amount of matter in an object and weight is a measure of the gravitational force on an object.