Download 1 In free fall, when two objects (one twice as massive as the other

Terminal Velocity Date ________
When objects are in free fall, the air resistance (__________ _________) is negligible and the only force on the falling object is the force of _____________________
which is _______________.
In free fall, when two objects (one twice as massive as the other one) are dropped they fall with the same acceleration. Why?
The object with twice the mass is attracted to the Earth
with more force (2F).
Doubling the force means _____________ the acceleration.
Doubling the mass means ___________ the acceleration.
The ratio of force to mass is the ______________.
In free fall, the acceleration is _____________, _________________.
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Nonfree Fall ­ Air resistance cannot be ignored!!!
When a rock is dropped in the air it accelerates because
the weight of the rock (Fg) (downward force) is greater than
the force of air resistance (R) (upward force).
There is a net force downward so the rock _____________________ downward.
As the speed of the rock increases, there is greater
number of air molecules that the object moves through
each second.
The force of air resistance (upward force) gets
greater and greater.
There is still a net force downward so the rock
______________________ downward.
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As the rock gains speed eventually the force of air
resistance increases until the air resistance (upward
force) equals the weight of the falling object
(downward force).
Now the net force is _________________
and the acceleration is _____________.
The object has reached _____________ __________.
The downward force of gravity is _________ in magnitude
but ______________________ in direction to the upward force of air resistance.
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Terminal velocity when jumping out of a helicopter
The person has a mass of 100 kg. So Fg = mg = 100 kg x ­9.8 m/s2 = ­980 N
As the person falls, the
R = 0 N
air resistance, R changes.
a = Fnet = Fg = ­980 N m
The air resistance is in the upward direction so it is positive.
R = 490 N
a = Fnet = The force of gravity on the person
Fg = ­980 N m
is always downward so it is
negative.
R = 980 N
a = Fnet = m
When the air resistance
__________ the force of
gravity on the person there
is _________ acceleration
and the person has reached
___________ ____________
Fg = ­980 N
R = 1470 N
a = Fnet = m
Fg = ­980 N
R = 1960 N
a = Fnet = m
Fg = ­980 N
When the parachute is
expanded fully the force of air
resistance upward equals the weight, Fg, of the person.
______________ ____________
has been reached again.
R = 980 N
a = Fnet = m
Fg = ­980 N
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Terminal velocity when jumping out of a helicopter
What happens if the mass of the person is doubled?
This person has a mass of 200 kg. So Fg = mg = 200 kg x ­9.8 m/s2 = ­1960 N
R = 0 N
Fg = ­1960 N
a = Fnet = m
a = Fnet = m
Fg = ­1960 N
R = 490 N
a = Fnet = Fg = ­1960 N m
R = 980 N
R = 1960 N
a = Fnet = m
Fg = ­1960 N
Why does is take longer for a more massive person to reach terminal velocity?
Terminal velocity depends on ________________ and ________________ ______________ of the object that is falling.
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Two smooth balls of the exact same size
are dropped from a high building. One ball is
made of wood and the other is made of iron.
Which ball encounters the greater force
of air resistance?
a) wooden ball
b) iron ball
c)...both the same
Why?
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As this daring Physics student
falls faster and faster through the air
her acceleration...
a) increases
b) decreases
c) remains the same
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Graphs of Falling Objects (The object is moving away from the frame of reference.)
Object does not reach
terminal velocity
Object reaches terminal velocity
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