Gravity
What is gravity? Gravity on Earth
Gravity is what makes everything with mass or energy attract each other.
The more mass the objects have, the more they pull. The closer the objects are, the stronger the pull.
You can’t feel the gravity of most objects because they are too small. But the Earth is so big that its gravity affects everything on it. Gravity also keeps the Earth and the other planets in their orbits around the Sun, and the Moon around the Earth.
An object falling toward the Earth speeds up as it goes.
But it doesn’t go as fast as it could, because the air pushes back on it. The more surface area the object has, the more air resistance it faces.
Different objects fall in different ways, depending on how gravity and air resistance affect them.
A feather, for example, is very light and has a lot of surface area, so it floats down slowly.
Sky divers know they will fall very fast because of gravity. They open a parachute to increase their surface area and air resistance, so they can slow down enough to land safely.
Understanding the Gravity of the situation At 3 times the distance, the pull is one ninth. This is called an 'INVERSE SQUARE' law. Gravity on other planets
To escape the Earth and travel into space, one has to overcome its gravitational pull.
From experimental data it can be shown that:
1. There is a gravitational pull between all bodies with mass. They attract each other.
2. Bodies with large masses have large pull. So big planets have high gravity.
3. The further they are from each other the smaller the gravitational pull between them.
4. Results show that at twice the distance the gravitational pull between the bodies is ¼.
The Moon is smaller than the Earth, so its gravitational pull is less than the Earth's. A person on the Moon can lift 5 times as much more weight as on Earth. The same weight will crush him on Jupiter.
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