Science 7
Notes 24
Gravity
Surface Area
Air Resistance
Free Fall
Think about it…
Which object will fall faster, a golf ball or
a piece of paper?
What factors on
Earth, affect the
rate at which an
object falls?
Explain how
satellites are able
to orbit the Earth
without floating
off into space
Explain how such
objects, as a
feather and a
bowling ball, can
hit the ground at
the same time if
released from the
same starting
point
simultaneously
At what rate
would all objects
fall in a vacuum
(with no air
friction)?
Describe the effect of
air friction and surface
area on a falling object.
Calculate the
acceleration of a falling
object.
Newton’s Hypotheses:
There is a force that makes all objects move toward each other and it
is called gravity
Gravity - force of attraction that exists between all objects in the Universe.
• Gravity depends on mass and distance, so an object close to earth’s
large mass will be forced toward it.
• That’s also why the smaller mass, Earth is forced into an attractive
orbit of the sun
Most objects falling through air experience a type of friction called air
resistance.
• Air resistance is not the same for all objects.
• The greater the surface area of the object the greater the air resistance.
For example, a man will fall faster without a parachute but slower with a
parachute
Free Fall
 An object is in free fall when the only force acting on the object is
gravity.
 Free-falling objects do not encounter air resistance.
Calculating Free Fall Acceleration
All objects in free fall accelerate at the same rate – 9.8 m/s² regardless of their mass.