2.6 Air
Resistance
A cannonball has another force slowing it down.
It is the result of air resistance.
The molecules in the air act with a frictional force slowing the object
down in both the x and y direction. The
faster the object is moving the more the frictional force.
For
a person jumping out of an airplane, it might seem like they will continue to
accelerate toward earth at 9.8 m/s2 until the splatter their brains
on the surface. At some point, the
skydiver’s air resistance (frictional force) equals that of the gravitational
force and the speed at which they
are moving is called the terminal velocity.
Of course, they further slow themselves down with a parachute.