Transcript Free Fall - Haiku Learning

Free Fall
Free fall occurs whenever an object
is acted upon by gravity alone.
Object that is dropped…
 What do you notice about the motion of
the object?
– Initial speed is zero
– The speed increases as it falls
– The longer it falls the faster it travels
– The object is accelerating.
Object tossed upward…
 What do you notice about
the motion of the object?
– On the way up its speed
decreases
– At the top, it stops and
reverses direction.
– The speed increases as it
falls back down.
Why does this happen?
 What causes things to move downward
towards the Earth?
– Acceleration due to gravity
– Gravity pulls objects toward the earth
– Free fall occurs whenever an object is acted
upon by gravity alone.
Why?
 What are the factors do you think affect how
fast an object will fall to the ground?
Let’s test it…
 What happens when two objects of different
masses dropped at the same time?
– The objects will hit the ground at the same time
Galileo & the Leaning Tower of Pisa
 In the Sixteenth Century, it was assumed
that the acceleration of a falling object
would be proportional to its mass.
– Example: a 10 kg object was expected to
accelerate ten times faster than a 1 kg object,
according to Aristotle.
 Galileo Galilei (1564-1642) came along
and put Aristotle's theories to the test.
Galileo’s Experiment
 Galileo verified his theories
through experimentation and
careful observation.
 Galileo dropped two objects
with unequal masses from
the Leaning Tower of Pisa.
 The two objects struck the
ground at the same time.
The Acceleration Due to Gravity
 The acceleration due to
gravity on Earth is…
a = 9.81 m/s²
a = 22 mph or 32 feet/s²
 The acceleration due to gravity varies with
location.
– greater at the poles than at the equator.
– greater at sea level than in higher elevations.
Paper and Pencil Experiment
 How are the speed of the flat paper and
pencil different?
– air resistance causes the paper go slower
 What happens if the paper in a ball instead
of flat?
– They hit the ground at the same time.
Terminal Velocity
 A free-falling object
reaches terminal velocity
when the downward
force of gravity equals
the upward force of air
resistance.
– 120 mph or 55 m/s
– Example Skydiving
(videos)