Gravity pulls things down — Physical education, 7–10
Gravity is the pull between objects, especially the Earth and everything near it. Physical education, 7–10 years.
Earth pulls us
Gravity is an invisible pull between things that have mass. Earth is enormous, so its gravity pulls people, rain, balls and loose objects towards the ground. Gravity also helps the Moon stay near Earth and keeps planets moving around the Sun, although those movements are harder to see.
Why do things fall?
People needed to predict what would happen when they dropped tools, built walls or threw objects into the air. Gravity explains why released objects do not simply float away and why rain comes down. Long ago, careful observers compared falling objects and the paths of the Moon and planets to find one idea linking them.
Example: dropping a ball
Leo holds a ball 2 metres above the ground and lets go without throwing it. Gravity pulls it down, so its height changes from 2 metres to 1 metre, then to 0 metres when it reaches the floor. It may bounce because the ball squashes against the ground and pushes back, but gravity keeps pulling it down after each bounce.
The common mix-up
Many people think a heavy object must fall faster than a light one. That seems reasonable because heavy things are harder to lift. But without air resistance, a heavy ball and a light ball dropped together speed up in the same way. A feather falls slowly in air mainly because air pushes against its wide, light shape.
Gravity all around us
Gravity keeps your feet on the ground, makes a ball return after a throw and brings water downhill in a stream. Builders allow for gravity when they make roofs, stairs and dams. Space missions also use gravity: a spacecraft can swing past a planet and gain a changed path without using all its fuel.
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