Gravity
...entire existence of the
universe. Some people think that gravity
consists of particles called gravitons,
which travel at the speed of light. The
only thing we do know is how gravity
operates in different parts of our universe.
Without gravity, there would be no space
and time.
There is a legend that says that Galileo
once dropped two objects off the Leaning
Tower of Pisa to show that the heavier of
the two objects
dropped faster. If a feather and hammer
were the two objects he used then
obviously the hammer would hit the
ground first. This is due to air resistance,
which is the force air exerts on a moving
object. This force acts in the opposite
direction to that of the object's motion. In
the case of a falling object, air resistance
pushes up as gravity pulls down, which
causes the object to slow down. When
Galileo's experiment was repeated on the
moon, the hammer and the feather hit the
ground at the exact same time. This is due
to
the fact that the moon has no atmosphere.
Therefore, air resistance doesn't exist on
the moon. Also, the amount of air
resistance on an object depends on the
speed, size, shape, and density of the
object. The larger the surface area of the
object, the greater the amount of air
resistance on it. This is why feathers,
leaves, and sheets of paper fall more
slowly than pennies, acorns, and
crumpled balls of paper.
There is another legend that states that
when Newton was lying against a tree in
an orchard, he was struck on the head by
an apple. He wondered what provided the
acceleration for the apple to fall to the
ground. Was this a force of the earth on
the apple? If so, then the apple must exert
a force on the earth according to
Newton's law of action/reaction forces.
Newton applied this theory unto the
planets, which orbit the sun. He found by
studying astronomical data, that...
View Full Essay
