CONTENTS Universal Force Gravity Keeps Pulling Newton s Law of Gravitation IO Newton s Ideas About Mass and Gravity Newton's Ideas About Distance and Gravity Earth's Moon I2 14 16 The Solar System Galaxies 18 Human Made Satellites 20 22 24 26 Astronauts and Centrifugal Force Gravity and Tides Gravity and Erosion on Earth A Mysterious Force Glossary For More Information Index 28 30 31 32
UNIVERSAL N A FORCE Gravity is a pulling force that works across space Because of gravity all objects in the universe attract all other objects This force is what keeps everything there is from flying apart You see gravity work every day Animals plants buildings X and even air are all affected 7 by gravity If you drop a book gravity is what pulls it to the A ground Even your body has gravity That s because you Watch out Gravity makes these falling books drop to the
orbit of the Moon around Earth Gravity keeps the Moon moving in an orbit around Earth Moon pull of the Moon and Earth on each other Earth pull of gravity that changes the path of the Moon path the Moon would naturally take have mass COMPARE AND CONTRAST Gravity is also very important in outer space Gravity keeps the Moon in orbit around Earth and it keeps all the planets in orbit around the Sun Think of gravity like a magnet pulling objects together Mass is the amount of matter or stuff in an object Which has more mass a beach ball or a bowling
