Free fall and Air
Resistance
Terminal Velocity
Free Fall

Free-fall: Objects in free fall have only the force of
gravity acting on them and the effect of air-resistance is
so small that it can be neglected.

“ All objects in free-fall will have the same rate of
acceleration regardless of their mass. This is the
constant that relates mass and weight of an object”
Visual Reference
Terminal Velocity
 The
two most important factors affecting air resistance
are:
 Speed
of the moving object
 Surface
 An
area of the moving object
object that encounters air resistance eventually
reaches a velocity called ‘terminal velocity’.
Terminal Velocity
 At
terminal velocity, force due to air resistance is
exactly equal and opposite to the force of gravity
acting on the object. Result:
 Acceleration
due to gravity is zero!!
OR
 object
experiences ‘weightlessness’!!
Visual Reference
Heavier Objects
 If
there is air-resistance, why do heavier objects fall
faster?
 Answer: Since the amount of air resistance depends
upon the speed of the falling object, a more massive
object will continue to accelerate to higher speeds in
comparison with a lighter object, until it encounters
an amount of air-resistance that equals their
greater weight or force of gravity.
 So
the terminal velocity of a heavier object will be
higher
Visual Reference
P.S.
If you drop an elephant from a sufficient height
so that it has long enough time to encounter
enough air resistance to balance the force of
gravity, it will probably happen at an extremely
high terminal velocity before it hits the ground.
 !!Ouch!!