Newton’s Cradle

Sir Isaac Newton was the first scientist to formulate a theory to explain gravity, and he did it over 300 years ago! Legend has it that while Newton was in his garden, an apple fell on his head. He wondered what caused the apple to fall. Why didn’t it fall up, or sideways? At that moment, he realized that the same force that causes the apple to fall towards the earth also causes the moon to orbit the earth and the planets to orbit the sun…

Gravity is a force that brings objects together. All objects that have mass have gravity and are therefore attracted to each other; the greater the object’s mass, the greater the force of gravity. Since Earth is really large, it pulls all objects on it towards its center, or down. Gravity undoubtedly helps life on Earth; without it, objects around you would float away into space. Gravity keeps your bed on the floor and the soup in your spoon. It keeps the water in the oceans and makes rain fall down. But gravity also hinders people in many ways. It makes heavy objects hard to lift, it makes space travel very difficult and expensive, it makes climbing up a long flight of stairs exhausting.

Newton’s Law of Universal Gravitation can be used to describe many phenomenon associated with gravity. It describes the motion of all objects on Earth. Scientists used it to go to the moon and today to send spacecraft to other planets.