Gravitation Gravity is the force of attraction between masses. It's the thing that pulls you down to earth. Newton's law of gravitation Why are you sticking to your chair (ignoring the spilled glue)? Why does the earth orbit the sun (or does it)? How high could I throw my dog on the moon? Gravitation defines our everyday life and the structure of the universe.
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Gravity is, quite simply, the force that holds together the universe. People are accustomed to thinking of it purely in terms of the gravitational pull Earth exerts on smaller bodies—a stone, a human being, even the Moon—or perhaps in terms of theSun's gravitational pull on Earth. In fact, everything exerts a gravitational attraction toward everything else, an attraction commensurate with the two body's relative mass, and inversely related to the distance between them. The earliest awareness of gravity emerged in response to a simple question: why do objects fall when released from any restraining force? The answers, which began taking shape in the sixteenth century, were far from obvious. In modern times, understanding of gravitational force has expanded manyfold: gravity is clearly a law throughout the universe—yet some of the more complicated questions regarding gravitational force are far from settled.