# This is an essay I did on explaining how gravity works as well as how it effects the tides... How high tide and low tide work

Essay by SonicHigh School, 11th gradeB+, January 2003

Introduction

"Gravity is a force of attraction that exists between any two masses, any two bodies, any two particles. Gravity is not just the attraction between objects and the Earth. It is the attraction that exists between all objects". (NASA gravity 2000) Gravity is a very essential part of life on earth. We are in the exact position in the sun's gravitational field to keep us in orbit and keep life ongoing on our planet. Gravity is a downward force on any body of mass, the larger the mass of the body, the stronger the gravitational force. On earth the force is 9.8 N/Kg (Newton's per Kilogram) roughly, depending on where you are on earth.

Gravitation

The original idea of gravity was discovered by Sir Isaac Newton (Jacob 1999). It is said that Newton was sitting under

an apple tree and an apple fell from the tree striking him on the head.

(What probably happened was that he watched an apple fall from a tree.) He concluded that there must be a force pulling all objects towards the ground, such as the apple and himself, and because the apple started at rest, there must be acceleration due to that force. Later with his invention of the telescope, he discovered that larger bodies have a stronger gravitational pull. It had been previously proven that the earth and other planets orbited around the sun. Because the sun was the largest body in the solar system, Newton concluded that larger bodies had larger and stronger gravitational fields.

As seen above, gravity is a force affecting 2 bodies. This is not totally exact because it does not factor in air resistance and friction. Even though gravitational acceleration is constant, air resistance affects free fall. For instance, if you took a sky diver and a...