SECTION 1 (PART 3) – Falling
Objects
AIR RESISTANCE
 When an object falls, gravity pulls it
down.
 Air resistance works opposite of gravity
and opposes the motion of objects that
move through the air.
AIR RESISTANCE
 Air resistance causes different objects
to fall with different accelerations and
different speeds.
 Amount of air resistance depends on
the speed, size, and shape of the object.
WHAT IF AIR RESISTANCE DIDN’T EXIST?
 This shows a feather and an apple falling
in a vacuum.
 There is no air resistance in a vacuum so
the feather and apple fall with the same
acceleration.
 Outside of the vacuum, the apple falls
much faster due to its mass and shape.
TRUE STORY – CHECK IT OUT!
Feather and Bowling Ball in a Vacuum
TERMINAL VELOCITY
 As an object falls faster, air resistance
increases.
 Eventually the upward air resistance
will be equal to the downward force of
gravity causing the net force on the
object to be zero.
TERMINAL VELOCITY
 Terminal velocity: highest speed a
falling object will reach
 Terminal velocity depends on size,
shape, and mass of the falling object.
TERMINAL VELOCITY
The force of air resistance on an open
parachute balances the force of
gravity.
The parachute opens and the
terminal velocity of the sky diver
becomes small enough that he/she
can land safely.
TERMINAL VELOCITY
 https://www.youtube.com/watch?v=p0I
ZsfzDS4s
BONUS MYTHBUSTERS!
http://www.youtube.com/watch?v=PHxvMLoKRWg