|There is a legend which says that while lying against a tree in an
orchard, Isaac Newton was hit on the head by a falling apple. What made the apple fall to the
ground? Was it a force from the earth on the apple? From this event, it is supposed, Newton
theorized about the force of gravity. He explained the motions of the apple, and the earth and
other planets around the sun as mutual attractions to each other. This attraction was called the
force of gravity. The more mass or volume each object has, the greater the force of attraction.
As the objects increase their distance apart, the attraction gets less or decreases.
Without gravity, we would never be able to keep our feet on the ground, and at the same time,
not be able to move off the ground. Without gravity, the moon would move in a straight line away
from the earth; gravitational force of the earth however pulls or attracts the moon to orbit
around it. Gravity also keeps planets on orbit around the sun in the solar system.
Imagine this, when you are biking uphill, the earth's gravity is pulling you back down the hill,
so that makes it hard to bike uphill. On the other hand, when you finally reach the top and you
are biking downhill, the earth's gravity is pulling you down the hill making your bike speed
faster downhill. In fact, anything going downhill gains speed as the earth's gravitational force
is pulling it down.