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A set of slides created to teach Falling Bodies and vertical motion to students following the South African National Science curriculum (NSC CAPS) in Cape Town.
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For FULL presentation click HERE >> www.warnescience.net
Falling Bodies (Vertical Motion)
K Warne
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For FULL presentation click HERE >> www.warnescience.net
Mass & Weight
Mass (kg):
• This is a measure of the
amount of matter
(number of kilograms)
that makes up a body.
Weight (N):
• This is the force of gravity
exerted on a body’s mass by
the earth (planet).
Fg
1 kg
1 kg
1 kg
G10 Revision
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98 N
Falling ObjectsTwo different object with different masses will FALL at the same RATE.
• The force of gravity on 1kg of mass is 9.8 N.
• Each unit of mass has the same force on it!
• Each mass unit will have the SAME ACCELERATION.
1kg
9.8N
9.8kg1kg
9.8N
1kg
9.8N
1kg
9.8N
1kg
9.8N
1kg
9.8N
Weight = mass x 9.8
Force of
gravity on the
mass (N)
Amount of
matter in
the object
(kg)
Gravitational
acceleration
(m.s-2)
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Gravitational Field Strength
• The weight of a 5kg bag of sugar on each planet.
g = 9.8 N.kg-1 g = 3.8 N.kg-1
A gravitational field causes masses inside it to experience a
force of attraction.
Gravitational field strength = Gravitational Force per unit mass
g = F/m (N.kg-1)
g = 23.6 N.kg-1
5kg 5kg…..N ….. 5kg……….
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Finding “g” by Pendulum• The cotton is burnt to release the plumb bob.
• The vertical distance is measured to where the plumb bob …………………………...
• The distance is fallen in …………………….. ……………………………………………..
• Readings: …………….., …………………
S = ………………………
• The time is measured for ……… complete oscillations to give a ……………….. reading.
• If the time for 10 oscillations is 16,6s - the time for ¼ oscillation is …………………...
• If the distance fallen is …………..m.
• Acceleration or “g” can then be calculated.
a = …………………………………………….
s
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Motion of Falling objectTime (s) Displacem
ent (m)
Average
Velocity
Instantaneou
s Velocity
(m.s-1)
Accelerati
on (m.s-2)
0 0 0 0 10
5 5 10 10
20 10 20 10
45 15 30 10
4 80 20 40 10
5 125 25 50 10
6 180 30 60 10
1
2
3
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Fg =mg
1. Object about
to start
falling. V=0
W=mg
2. Object is
falling. V>0
Friction
a 9.8 m/s2
Friction=Fg
a= m/s2
TERMINAL VELOCITY
3. The object now
moves with
TERMINAL
VELOCITY.
An object is dropped from REST.
V = max
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• Falling objects …………………………….. at …………………..
• The velocity increases every second and the ……………………………… every second increases as well.
• The ……………………………… increaseswith every second that the object is falling.
• Each particle applies a small force on the object and the until the …………………… ……………………… to the downward force of gravity.
• There is …………………………. force and therefore no acceleration.
• The object will continue to move at …………. ………………….
• This velocity we call ……………………. The terminal velocity of an object is dependant on its size and shape.
Terminal velocity
From World Book © 2002 World Book, Inc., 233 N.
Michigan Avenue, Suite 2000, Chicago, IL 60601.
All rights reserved. World Book illustration by David
Cunningham
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G r a v i t y
Equations of motion for free fall and vertical
projectile motion
An object is in “…….. ……………” if:
• it is moving ….. or ……….. without ……………. other than ……………
• we ignore ………. ……………..
• we can substitute “g” for “a” in equations because the ………….. …………………. is gravity.
gsuv
gtuts
gtuv
2
2
1
22
2
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A ball falls freely from rest.a) velocity vs. time
b) displacement vs. time
c) acceleration vs. time
d) speed vs. time
e) distance vs. time
vt
xt
at
t
v x
t
a) b)c)
d) e)
+Consider only the period of free
fall and take upward direction as positive (+ve).
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A ball is thrown vertically upward and returns
to the throwers hand.a) velocity vs. time
b) displacement vs. time
c) acceleration vs. time
d) speed vs. time
e) distance vs. time
Consider only the period of free fall and take upward direction as positive (+ve).
vt
xt
xt
t
v s
t
a) b)c)
d) e)
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Hi -
This is a SAMPLE presentation only.
My FULL presentations, which contain a lot more more slides and other resources, are freely
available on my resource sharing website:
www.warnescience.net(click on link or logo)
Have a look and enjoy!
WarneScience