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## Chapter 2: Kinematics in One Dimension

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### Title: Chapter 2: Kinematics in One Dimension Author: Daniel Morgan Middle School Last modified by: Administrator Created Date: 2/8/2007 12:41:39 PM – PowerPoint PPT presentation

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Title: Chapter 2: Kinematics in One Dimension

1
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2
Ocean Science!
• Monday
• Review 20-2 reading guide questions.
• Review for tomorrows quiz
• Start frozen seas video
• Tuesday
• 20-2 Ocean Life Quiz
• Wednesday
• Research questions
• Finish Frozen seas video
• Thursday
• Ocean resources
• Friday
• Ocean Resources

3
Improvements
• Needs reordered according to gravity notes for
real.
• Yes, definitely needs reordered
• Look up common misconceptions address them
• Use physics website more!
• More on weightstudents never get how to
calculate weight! Is important later too.
• Weight on other planets!
• Make peanut butter jars with different weights
for different gravity!
• Itd be coolest if it were a regular weight on
Earth!

4
Bonus!
• The acceleration due to gravity on the surface
of Jupiter is 25.9 m/s2. How many pounds would a
80.0 kg person weigh there?
• (1.00 lb 4.46 N)

5
Bell Work 4/8/13
• New Bell Work Sheet!
• How many Newtons would a 885.0 kg object weigh on
Earths surface? (Use F ma, a 9.81 m/s2)
• Convert this to lbs.

6
Bell Work 4/22
1. A 45.0 kg ball experiences a force of 441.45 N.
What will its acceleration be?
2. A 90.0 kg ball experiences a force of 882.9 N.
What will its acceleration be?
3. W5SAYWoS

7
Schedule
• Wednesday
• See quizzes?
• Review labs
• Law of gravity notes!
• Thursday
• Law of gravity notes!

8
• Turn in your newtons laws demos lab!
• Make sure your grade sheet update! Show me for
some pts!!! 10 pts!!!!!

9
• Today you are going to
• take notes on gravity!
• So you can
• explain what affects the force of gravity
predict the gravity between different objects
• Youll know youve got it when you can
• Answer the questions at the end of slide show

10
The 4 Fundamental Forces
11
Gravity!
• What does it do?
• Holds objects on Earth
• Makes objects fall
• Keeps satellites in orbit!

12
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13
Gravity!
• Gravity is the attraction between any two objects
that have mass.
• Its actually the weakest force!
• Its magic!!
• We dont really understand it (but then, thats
true of most fundamental stuff)
• Sir Issac Newton wrote the law of universal
gravitation.

14
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15
Gravity Mass
• Universal gravitation equation ?
• G 6.67 x 10-11
• 2 things affect the force of gravity ___________
and _____________
• The force of gravity is ___________________
related to mass.

16
Gravity Mass
• Gravity is the attraction between any two objects
that have mass. Why dont we notice the force of
gravity between all objects?

6.67 x 10-11 (50 kg)(5.97 x 1024 kg)
(6,371,000 m)2
491 N 110 lbs
6.67 x 10-11 (50 kg)(1.0 kg) (1 m)2
3.35 x 10-9 N 0.000 000 003 35 N 0.000 000 000
754 lb
17
• Gravity is the attraction between any two objects
that have mass. Why dont we notice the force of
gravity between all objects?

Even though the force of gravity between less
massive objects is, it would be noticeable if it
were the only force around. However, on Earth
the gravity of Earth overpowers these other
gravities, not to mention the fact that the
gravity between you other objects are pulling
in all sorts of directions, so they cancel out.
Far away from planets, the gravity of semi
large objects would have an effect. Its one way
we could deflect an oncoming asteroid!
18
Gravity Distance
• Universal gravitation equation ?
• G 6.67 x 10-11
• The force of gravity is ___________________
related to distance.

19
Gravity Distance
• The force of magnetism
• Which is stronger, gravity or magnetism?
• How are gravity and magnetism similar?
• How are gravity and magnetism different?

20
Gravity, Mass, Distance
• What happens to the force of gravity if
• mass doubles?
• distance doubles?
• So gravity depends more on ___.

21
Whats this table tell you?
22
• Would your mass or weight be any different on the
moon? Why?
• Would your mass or weight be any different on the
top of a tall mountain? Why?

23
• What is the weakest fundamental force?
• Who discovered the law of gravity?
• What 2 things does the force of gravity depend
on?
• Which does it depend on more?
• The force of gravity is directly related to ___,
and you can tell because ____
• The force of gravity is directly related to ___,
and you can tell because ____
• You would weigh ___ on the moon because _____.
• You would weigh ___ on Mt. Everest because
_____.

24
• Today you are going to
• take notes on weight freefall
• So you can
• calculate weight
• explain how objects freefall
• explain the behavior of projectiles
• Youll know youve got it when you can
• Answer the questions at the end

25
• Bell Work 5/5/14
• Do 1-7 on the Gravity and Projectile Motion Study
Guide 1
• Free Fallin Tom Petty https//www.youtube.com/wat
ch?vjVa0sISCjXc

26
Freefall!
• Freefall - when gravity is the only force acting
on an object.
• All things on Earths surface fall with same
acceleration (_______).
• If 2 objects were both dropped from the same
height, they would hit the ground at the same
time. Why dont we notice this?
• Strobe light drops of water!

27
Air Resistance!
• Air resistance keeps all objects from falling
with the same acceleration on Earth.
• Terminal velocity the fastest an object can
fall due to air resistance
• Happens when force of air resistance weight
• FNET 0, therefore a _______!
• Moon Hammer Drop
• Feather in vacuum
• Elephant and feather on physics classroom

28
7 Minutes of Terror
• Landing
• 13,000 mph to 0 mph in 7 min
• What are some differences between Earth and Mars
that
• affect how things
• fall there?

29
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30
• Jill and Nick have a task. They both have to
push a cart down the hall with an acceleration of
5.0 m/s2.
• Jills cart has a mass of 10.0 kg. How hard does
she have to push it?
• Nicks cart has a mass of 20.0 kg. How hard does
she have to push it?
• Even though Nick pushes his cart twice as hard,
his cart accelerates at the same rate because

31
Freefall!
• Why do all things fall with the same
acceleration? Shouldnt heavier objects fall
faster?
• Earths force of gravity on an object is its
weight.
• On the surface of Earth 1.0 kg weighs about 9.81
Newtons.
• A 5.0 kg object weighs 44.05 Newtons. Calculate
its acceleration when dropped.
• A 10.0 kg object weighs 98.1 Newtons. Calculate
its acceleration.

32
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33
Why is the acceleration for everything the same?
• If something has twice the weight, it also has
twice the inertia, therefore its twice as hard
to accelerate.
• Gravity is like horse drawn carriages, or a bunch
of tiny magnets!
• Would two pieces of clay fall faster if combined?

34
Bell Work 4/25/13
1. What 2 things determine the strength of the force
of gravity?
2. Do all objects fall with the same acceleration on
Earths surface? Why/Why not?
3. Do objects with twice the weight fall with the
same acceleration? Why/Why not?
4. Which falls faster, a bullet thats fired
horizontally or a bullet thats dropped? (or
neither)

35
Weight
36
Weight Weight dont tell me!
• Weight - force of gravity between an object a
planet.
• FW ma (a is acceleration due to gravity)
• How much would a 1.00 kg object weigh on the
surface of Earth? In lbs?

37
• Today you are going totake notes on projectiles
and circular motion.
• So you canpredict and explain the motion of
projectiles objects in circular motion
• Youll know youve got it when you can
• Accurately answer the questions

38
Schedule
• Monday
• Gravity Notes Questions
• Tuesday
• Projectile Circular Motion Notes Questions
• Wednesday
• Orbits!
• Thursday
• Review Questions Begin Egg Drop Project
• Friday
• Build Egg Drop Project

39
7 Minutes of Terror
• Landing
• 13,000 mph to 0 mph in 7 min
• What are some differences between Earth and Mars
that
• affect how things
• fall there?

40
Free Fall Reaction Time
• http//www.brianmac.co.uk/rulerdrop.htm

41
Projectile Motion
42
Projectile Motion
• Projectile motion motion in which an object
(projectile) is thrown near a planets surface,
and gravity is the only force acting on it
• Ex. Thrown football, bullet shot, cow launched
from catapult.
• Projectiles follow curved path called a parabola.

43
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44
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45
Projectile Motion
• Projectiles are in freefall!

46
Projectile Motion
• has horizontal (left right) vertical (up
down) motion.
• The horizontal and vertical motion are
independent.
• They dont affect each other!
• Which will hit the ground first, a bullet fired
from a gun or a bullet dropped from the same
height?
• Mythbusters!!

47
Horizontal Projectile Motion
• The horizontal (Vx) velocity of a projectile
doesnt change!
• This makes sense because the net force in that
direction is ____________.

48
Vertical Projectile Motion
• A projectile
• takes as long to go up as it does to come down to
the same point at which you released it.
• It will be going the same speed in the opposite
direction when it reaches its original height.
• At its maximum height
• vy
• t

49
Projectile Motion
• What 2 things affect the distance of a
projectile?
• What angle will launch a projectile farthest?
• What angles will launch projectiles the same
distance?

50
Bell Work 4/26/13
1. What is the shape of a projectile?
2. What angle will launch a projectile farthest?
3. What angles will launch projectiles the same
distance?
4. List 3 things that affect the range (distance) of
a projectile.

51
Projectiles with Air Resistance
• The optimal angles to send balls flying the
farthest distances are around 40. For example,
for kicking or punting a football, you yield the
largest distance at a launch angle between 35
and 40. If you throw a small ball, such as one
used in track and field events or a baseball, the
ball is much smaller. Thus, the friction plays a
smaller role in the movement. Then the best angle
is almost 45.

52
Projectile Motion
53
Shoot a Monkey!

54
Citing a rifle in
55
• Can an object be moving upwards if nothing is
pushing it?
• Can an object be moving horizontally if nothing
is pushing it?
• Is force required to keep an object in motion?
(Newtons ______ Law)

56
Bell Work
• Which direction do you think the doughnut will
travel when the string breaks?

57
Schedule
• Monday
• Check HW (Study guide), Review questions, Egg
Drop
• Tuesday
• Notes on Circular Motion Orbits Egg Drop
• Wednesday
• Notes on Orbits Weightlessness Egg Drop
• Thursday
• Review Questions Finish Egg Drop Project
• Friday
• Test Egg Drop Project

58
• Today you are going totake notes on circular
motion.
• So you canunderstand the direction of
acceleration velocity in circular motion and
centrifugal force.
• Youll know youve got it when you can
• Accurately answer the circular motion questions.

59
Circular Motion
60
Circular Motion
• Objects in circular motion are accelerating
towards the center
• Centripetal force force acting on an object in
circular motion pulls towards center of circle

61
Circular Motion
• Shape of horizontally thrown projectile

62
Centripetal Force
• Force diagram of object in circular motion

63
The forbidden F word!
• Centrifugal force imaginary center fleeing
force on an object in circular motion
• NOT REAL
• Caused by inertiathe object wants to keep
traveling in a straight line

64
Car driving in circles
65
The forbidden F word!
• Circular motion demos
• Why does it stay there? (a law)
• What force acts on it? What direction?

66
Demos Puzzles
• What provides the force
• Toms puzzle
• Penny in balloon
• Marble tape
• Ball on string
• Color changing ball
• Ball on string through tube with weight

67
• Question A ball is being whirled around by a
string. If the string suddenly breaks (or is let
go), what direction will the ball travel A, B,
C, or D? (Neglect gravity) HAMMER THROW!!!

68
Doughnut on a string!
related

69
• Answer Path ___
• While attached to the string, the ball is forced
to follow a curved path. But once the string is
gone, no force is exerted and (law of inertia) it
follows a straight-line path.

70
Bell Work 5/1/13
• Answer questions 1-5 on the back of your Gravity
Projectile Motion Study Guide.

71
• Today you are going totake notes on orbits!
• So you canunderstand how satellites, moons, and
planets orbit things.
• Youll know youve got it when you can
• Accurately answer the questions.

72
Projectile Motion Orbits
73
Projectile Motion Orbits
• Force diagram of object in circular motion
• (this should be earlier in slide show, when
circular motion first mentioned)

74
Projectile Motion Orbits
• Objects orbiting Earth are in free fall!
• Theyre falling!
• Gravity acts as the centripetal force
• Cannonball!

75
Satellites!
76
Earth Satellites
Earth satellite - projectile moving fast enough
to fall continually around Earth rather than into
it. The orbital speed for an object closely
orbiting Earth is about 8.0 km/s. That is 29,000
km/h (18,000 mi/h).
77
Earth Satellites
In the curvature of Earth, the surface drops a
vertical distance of nearly 5 meters for every
8000 meters tangent to its surface.
78
Earth Satellites
For a satellite close to Earth, the time for a
complete orbit around Earth, its period, is about
90 minutes.
79
Earth Satellites
A satellite must stay 150 kilometers (94 miles)
or more above Earths surface. Why cant we put
a satellite into orbit at low altitudes on Earth?
80
A satellite in circular orbit close to Earth
moves tangentially at 8 km/s (5 mi/s). During
each second, it falls 5 m.
81
Escape Velocity
To escape Earths gravity, an projectile must be
launched at a velocity of 11.186 km/s 25,000
mph. Rockets arent projectilesthey dont need
to go this fast. The firing of the rocket
provides a constant force. Pioneer 10, launched
from Earth in 1972, escaped from the solar system
in 1984 and is wandering in interstellar space.
82
Space Junk!
83
Bell Work 4/8/11 4 minutes
• Convert the following weight to Newtons.
A. 16 lb bowling ball
Find the mass of the
above in kilograms.
• Explain how satellites orbit Earth.

84
Bell Work
1. Get your notes study guide out finish the
last questions.

85
Schedule
• Monday
• Gravity Notes Questions
• Tuesday
• Circular motion! Build Egg Drop Project
• Wednesday
• Orbits! Build Egg Drop Project
• Thursday
• Review Questions Build Egg Drop Project
• Friday
• Review Build Egg Drop Project
• Monday
• Test!
• Tuesday
• Test Egg Drop Project

86
Weightlessness!
87
Weight Weightlessness
• How would it feel to be weightless?
• How do you feel your weight?

88
Weight Weightlessness
• What you feel as your weight is a sensation due
to the normal force
• Just because you dont feel your weight, doesnt
mean youre weightless!
• Astronauts in space are not really weightless.

89
Weight Weightlessness
• Astronauts are just in constant freefall! Nothing
is holding them up. They feel no normal force,
so they feel weighless. They float in the space
station because the space station is falling with
them.
• Since theres nothing holding them up, they feel
weightless!
• Drop Han Solo!

90
Weight Weightlessness
91
Would you like to be weightless?
92
Zero-G
93
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94
• People On Vomit Comet
related
• Water balloons in zero gravity http//www.youtube.
com/watch?NR1featurefvwpvgTqLQO3L4Ko

95
end
96
Freefall on planets
• What all is the same on the surface of Earth?
Figure out that everything else must be equal to
acceleration due to gravity.

97
Egg Drop!
• You may purchase more materials during project.
• Materials list (5 pts)
• Include quantity, description, price, total
price, and net price.
• Explain the purpose/advantage of each material
• Dont spend it all. You may purchase more
materials during project.
• Blue print (10 pts)
• Anyone looking at the blueprint should be able to
build it
• Everything must be to scale (1in 1 square)
• Explain how things are attached, lengths of
string
• Newspaper
• Half Sheet 11.5 x 22.7 Full sheet 22.7 x 22.7
• Dont break your egg!
• If you do, you will have to clean it up.
• Make sure to calculate average speed show all
work.
• Winners get a free homework pass!

98
Materials List
• Item Cost Total
• Full sheet of newspaper
• Straws
• 12 pieces of tape
• Net Cost

99
Egg Drop!
• Answer the following questions in complete
sentences on your graph paper.
• Explain how your design relates to what you know
about air resistance and freefall. How is it
going to cause the egg to fall slowly?
• If you had to name a possible problem with your
contraption, what would it be? (What might go
wrong?)
• Hopefully your egg stopped accelerating pretty
soon after you let it go. What 2 forces were
equal at this point?
• If there were 2 eggs in your basket, would it
have fallen faster? Why or why not?
• Were there any problems with your project? How
could you improve upon it (even if there werent
problems)?

100
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101
Bell Work 4/11/12
1. What is a satellite?
2. What are the forces acting on a satellite?
3. How long does it take a satellite to orbit Earth?
4. Can we see satellites with the naked eye?
5. How fast do you have to throw a ball to throw it
off of the planet?

102
• Pluto has a mass of 1125 x 1022 kg and an
equatorial radius of 1195 km. (a) Calculate the
acceleration due to gravity on the surface of
Pluto. (b) A python weighs 980 N on Earth. How
much would it weigh on Pluto?

MP 1024 kg rP 1195 km 1195000 m 1.195 x
106 m G 6.67 x 10-11 N m2/kg2
g G MP/rP2 g (6.67 x 10-11)(1024)/(1.195 x
106 )2 g 4.78 x 10-20 m/s2
WE 980 N gE 9.8 m/s2 gP 0.59 m/s2 WP ? N
WE mgE 980 m(9.8) 100 kg m
W mg (100)(4.78 x 10-18m/s2) 4.78
x 10-18 N
103
• The elephant and the feather each have the same
force of gravity.
• The elephant has more mass, yet both elephant and
feather experience the same force of gravity.
• The elephant experiences a greater force of
gravity, yet both the elephant and the feather
have the same mass.
• On earth, all objects (whether an elephant or a
feather) have the same force of gravity.
• The elephant weighs more than the feather, yet
they each have the same mass.
• The elephant clearly has more mass than the
feather, yet they each weigh the same.
• The elephant clearly has more mass than the
feather, yet the amount of gravity (force) is the
same for each.
• The elephant has the greatest acceleration, yet
the amount of gravity is the same for each.

104
Bell Work 4/8/11 5 minutes
• Convert the following weights to Newtons.
A. 16 lb bowling ball
B. 17 lb cat
• C. 20,000 lb truck
• Find the mass of the above in kilograms.
• If an object has reached terminal velocity, what
is the net force on the object? Whats its
acceleration?
• T/F An object in orbit is actually falling.

105
Bell Work 4/4/11 5 minutes
• START NEW MONDAY BELL RINGER FOR 4TH QUARTER ?
• Define mass according to chemistry and according
to physics.
• W5SAYW

106
Bell Work 3/30/12 5 min
1. Robbie can throw a 3.0 kg medicine ball with an
acceleration of 10.0 m/s2. What acceleration
could he give a 9.0 kg medicine ball? Show your
work!
2. If you were in a plane, would your weight or mass
change? Why?

107
• The moon has a radius of 1.74 million meters and
a mass of 7.32x1022 kg. In both MKS and FPS
units, determine the acceleration due to gravity
on the lunar surface.

M 7.32 x 1022 kg r 1,740,000 m 1.74 x 106
m a ?
a GM r2 a (6.67 x 10-11)(7.32 x
1022 kg ) (1.74 x 106)2
48.824 x 1011 3.02 x 1012
16.17 x 10-1
1.62 m/s2
108
Bell Work 4/11/11 5 minutes
• Mass (kg) Weight on Earth
• Newtons Pounds
• 1 kg ____N ____lbs
• 50 kg ____N ____lbs
• 0.102 kg ____N ____lbs
• _____ kg 500 N ____lbs
• _____ kg 50 N ____lbs
• _____ kg ____N 2,000 lbs
• W5SAYW

109
Bell Work 3/29/12 5 min
1. A force of 250.0 lbs acts on an object with a
mass of 8.0 kg. Whats its acceleration?
2. What is gravity?

110
Bell Ringer 4/1/11 2 min
1. If the mass of an object magically doubled, the
force of gravity between it and other objects
__________.
2. If the distance between two objects doubles, the
force of gravity between them is ____ what it
was.

111
Bell Work 4/7/11 5 minutes
• Use the conversions between lbs, kg, and N in
your notes to answer the following questions.
• What is the difference between mass and weight?
Give 2 units that measure weight and 1 unit that
measures mass.
• Change the following weights to Newtons.
12 lb bowling ball
117 lb teen

1600 lb car
• Find the weight of the following masses in
Newtons AND pounds.
• 1 kg 5 kg 1000 kg

112
• If Pandora has a mass of 5.00 x 1024 kg and a
• 6.00 x 103 km, find the weight of a 110 kg Navi
on Pandoras surface. (Pay attention to the
units!)

MP 5.00 x 1024 kg mN 110 kg r 6.00 x 103
km 6.00 x 106 m W Fg ?
Fg GMPm r2 Fg (6.67 x
10-11)(5.00 x 1024 kg )(110 kg)
(6.00 x 106)2 Fg 1019 N
113
Tips for using the G equation.
• Make sure you square r!
• Youll be dealing with big numbersdont forget
the exponents! x 10-11!

114
Satellite Motion
1. What is a satellite?
2. What are the forces acting on a satellite?
3. How long does it take a satellite to orbit Earth?
4. Can we see them with the naked eye?
5. How fast do you have to travel to get escape this
planet?

115
14.2 Circular Orbits
The speeds of the bowling ball and the satellite
are not affected by the force of gravity because
there is no horizontal component of gravitational
force.
116
14.2 Circular Orbits
• The satellite is always moving at a right angle
(perpendicular) to the force of gravity.
• It doesnt move in the direction of gravity,
which would increase its speed.
• It doesnt move in a direction against gravity,
which would decrease its speed.
• No change in speed occursonly a change in
direction.

117
14.4 Energy Conservation and Satellite Motion
For a satellite in circular orbit, no force acts
along the direction of motion. The speed, and
thus the KE, cannot change. What force or forces
hold satellites in orbit?
118
14.2 Circular Orbits
A satellite in circular orbit close to Earth
moves tangentially at 8 km/s (5 mi/s). During
each second, it falls 5 m beneath each successive
8-km tangent. What happens to the velocity of a
satellite as the distance from Earth increases?