The pull you never notice
What Is Gravity?
Everything with mass pulls on everything else. Earth just pulls hardest.
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Step 1 of 5
Things fall because something pulls them.
An apple does not choose to go down. Earth pulls it, with a force strong enough to accelerate it about 10 metres per second faster every second.
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Step 2 of 5
The apple pulls the Earth too.
The pull works both ways, with exactly equal force. Earth just has 10²⁵ times more mass, so its movement is far too small to notice.
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Step 3 of 5
More mass means a stronger pull.
A mountain pulls on you, but so weakly you cannot feel it. Earth is 10 million times more massive than the biggest mountain, so it wins completely.
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Step 4 of 5
Distance matters as much as mass.
Gravity fades with the square of distance. Move twice as far from the centre and the pull drops to a quarter — which is why the Moon is held gently.
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Step 5 of 5
Everything falls at the same rate.
Heavy things are pulled harder, but they also resist speeding up more. The two effects cancel exactly, so a hammer and a feather land together — if there is no air.
An Apollo astronaut actually did this on the Moon in 1971. They landed together.
The short version
Gravity is a mutual pull between every pair of masses — Earth just has enough mass to dominate.
Try it yourself
Drop a book and a sheet of paper. Now put the paper flat on top of the book and drop again. Same fall, because the air is out of the way.
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