Chapter One: Motion
Section 1.1 An object in motion
changes position
Position describes the location of an object.
The position, or location, of an object is described
relative to a reference point.
The choice of reference point affects how the
position is described.
For example, a city can be located by
measuring its direction and distance from another
city, or by using a grid system, such as the
longitude-latitude system.
Grid vs. Direction & Location

Peoria is located at
40N 90W (grid)

Peoria is about 85.5
miles NW of
Decatur. (direction &
location)
There are two ways to measure the distance an
object has traveled.
One is to measure the length of the path the
object followed.
Another is to measure the straight-line distance of
an object from its starting point.
This straight-line distance is called the
displacement of an object.
Distance vs. Displacement
Displacement
Distance
Reviewing ConceptsIf relatives living in different cities wanted
directions to your house, would you give them the
same or different directions? Why?
If you travel by car from Decatur to Chicago,
would measuring the path or displacement be a
better estimate for figuring distance?
If you traveled by plane from Decatur to Chicago,
would measuring the path or displacement be a
better estimate for figuring distance?
In the following activity, I would like you to describe the position of the ice cream cone.
in two different ways:
Using the grid
Using a another object for a reference point.
A
2
3
4
B
C
D
E
F
In the following activity, I would like you to measure the distance in two different ways:
Using the path traveled from the point A to the Bank.
Using displacement.
A
Section 1.2 Speed measures how
fast position changes
Position can change at different rates.
 Speed is a measure of how fast something moves
a particular distance over a given amount of time.
 *Speed=distance/time or S=d/t
 Average speed is the average of several
instantaneous speeds whose measurements are
taken over a specific period of time. (This is what
you are familiar with )

A distance-time graph shows how both distance
and speed change with time.
 You can use these graphs to determine the speed
of an object by calculating the slope of the line.
A positive slope means the object is moving away
from its starting point.
A negative slope means the object is moving back
towards its starting point.
 *Slope= change in distance/change in time=speed

Distance-Time Graph
Travel from Decatur to Woodstock
200
180
160
140
120
100
80
60
40
20
0
Distance
Time
0
0.5
1
0.5
2
2.5
Distance
0
0.5
1
0.5
2
2.5
3
0
35
68
105
142
175
207

Let’s pretend that graph shows you my travel from
Decatur to Woodstock. The train traveled at a
different speeds between cities. Here is a table of
information that will help you calculate speed and
average speed of the whole trip:
Time
Distance
0
0
0.5
35
1
68
0.5
105
2
142
2.5
175
3
207
To calculate speed from the starting point to the
first stop, you divide the change in distance by
the change in time. So (35-0)/(.5-0) = speed.
Speed= (35)/(.5)= 70 mph
To calculate speed from the first stop to the
second, divide change in distance by change in
time. So (68-35)/(1-.5) = speed.
Speed= (33)/(.5) = 66 mph
To calculate the train’s average speed for the whole trip, divide the total change in
distance by the total change in time: (207-0)/(3-0) = 69 mph
Velocity is speed in a specific direction
 Velocity is represented by a vector.
 A vector is a quantity that has both size and
direction.
 Vectors are shown with arrows.
 The longer the arrow, the faster the speed.
 The direction of the arrow indicated the direction
of motion.

Speed and velocity are not the same.
 If two runners run at the same speed in opposite
directions, they will have identical speed but
different velocities.
 p. 22 in textbook

These two arrow have different
speeds but same
direction…therefore, their
velocities are different
These arrows have the same
speed in different
directions….therefore their
velocities are different
Section 1.3 Acceleration measures how
fast velocity changes.
Speed and direction can change with time.
 Acceleration is the rate at which velocity changes
with time.
 Contrary to a popular misconception, acceleration
is not limited to increases in velocity but includes
any change in velocity. (It isn’t just speeding up,
but also slowing down and/or changing direction)

The following are examples of acceleration:

Speed increases

Speed decreases

direction changes (regardless of speed)

Acceleration can be calculated from velocity and
time.
 You determine acceleration from the change in
velocity and how long the change took. (The
saying “from zero to 60 in 20 seconds” is an
expression describing acceleration of a car. It is
like the rate at which you are speeding up or
slowing down)

Time
Distance
0
0
0.5
35
1
68
0.5
105
2
142
2.5
175
3
207
All of these checkpoints have varying velocities:
0-1= 70 mph
1-2= 66 mph
2-3= 74 mph
…..and so on
The formula for calculating acceleration is:

A=(Vfinal-Vinitial)/t

This is the information you saw on the last slide:
0-1 (half-hour of travel time)= 70 m/h
1-2 (half hour of travel time)= 66 m/h
2-3 (half hour of travel time)= 74 m/h
To calculate Acceleration from the first checkpoint to the second, subtract the initial
velocity from the final velocity and divide by time. A= (66-70)/1 = -4 m/h2
Turn to page 28 and do the example with me.
 Negative acceleration is a decrease in velocity
during a specific period of time.
 The acceleration formula yields a negative result
when the final velocity is less than the initial
velocity. (When you slow down)

A velocity-time graph shows how both velocity
and acceleration change with time.
 Turn to page 30 in your textbook. The graph on
the top is a velocity-time graph; compare it with
the distance-time graph for the same set of data,
which is shown below. The graphs show a boy (1)
starting and speeding up on his scooter (2)
coasting (velocity is constant), and (3) slowing to a
stop.

Section 2.1 Forces Change
Motion
A force is a push or a pull.
 Force in physics is defined as “a push or
a pull”. Some forces:
 require contact between objects, such
as friction and
 act at a distance, such as gravity and
electromagnetic forces.

Net force is the total force that affects an
object when multiple forces are combined.

The net force depends on both the
direction and the size of the individual
forces.

Ex: You can use the information
provided by net force to predict who would
win an arm wrestling match. Imagine a
Anderson Silva (MMA fighter) arm wrestling
Justin Bieber. Forces act in opposite
direction, but Silva’s will be much greater.
Therefore the net force acts against
Bieber’s and Silva will likely win.


To show you visually how to measure
net force, use the following:
1. Identify Forces to
Combine.
Combining Forces in the
same direction
Combining in opposite
directions
2. Put tail of second Force
arrow to tip of first.
Maintain length (size) and
direction.
3. Measure from tail of first
Force to tip of second
Force arrow.





Newton’s first law relates to force and
motion.
They key points of Newton’s first law are:
Objects with no net fore acting on them
either have constant or zero velocity
force is needed to start or change motion
Inertia is the resistance of an object to a
change in its motion; it is directly
proportional to the object’s mass.
Section 2.2 Force and mass
determine acceleration
Newton’s second law relates force,
mass, and acceleration.
 The key points of Newton’s second law
are that the acceleration of an object is

 Directly proportional to the force acting on
the object
 Inversely proportional to the mass of the
object
 In the same direction as the net force acting
on the object
 What
does Newton’s second law mean
exactly?
 Imagine you are trying to move a large
bookshelf into another room.
 Since force and acceleration have a direct
relationship, this means that the more force you
apply to the bookshelf the quicker it will
accelerate.
 Since acceleration and mass have an inverse
relationship, if you were to fill the bookshelf and
apply the same amount of force, it would not
accelerate as quickly.
Imagine the same amount of force is applied to each
bookshelf. The top bookshelf is the “full” shelf, the bottom
one is the empty one.
Newton’s second law is
summed up by the equation
 Force=mass x acceleration or F=ma
 Force is measured in Newtons (N).
 Since Force=mass times acceleration (kg
x m/s2), you can use the units of each of
these to determine the value of a
Newton.
 1 N is equal to 1kg x 1m/s2
 You can rearrange this equation to find
different values:
○ F=ma
m=F/a
a=F/m
Let’s review this relationship a
little bit more:
 F=ma
 If I increase acceleration, force must
increase
○
F=ma
 If I increase mass, force must increase
○
F= ma
 If I increase mass and want to apply the same
amount of force, acceleration must decrease
○
F= ma
 If I increase acceleration and want to apply the
same amount of force, mass must decrease
○
F= ma
Here is an example problem:
 Kayla is helping her mom buy groceries for her
and her little brother. The shopping cart is
accelerating at 5 m/s2. The force on it is 75 N.
What is the mass of the shopping cart & its
content?
 What do you know?
 What do you want to find out?
 Choose formula
 Substitute known values
 Calculate and simplify
Here is an example problem:
 Feynman, Alex, and Andrew are pulling a
trampoline. If their combined force is 1000 N
and the trampoline is 250 kg, what is the
acceleration of the trampoline?
 What do you know?
 What do you want to find out?
 Choose formula
 Substitute known values
 Calculate and simplify
Forces can change the direction
of motion.
 Force can change the direction of an object
without changing its speed if the force acts at right
angles to the motion.
 A force that continuously acts at right angles to an
object’s motion will pull the object into circular
motion.
 Any force that keeps an object moving in a circle at
a constant speed is called centripetal force.
 The centripetal force needed to keep an object
moving in a circle depends on the mass of the
object, the speed of the object, and the radius of
the circle.
○ Centripetal force = (mass x speed2)/radius
Here is an example problem:
 Jordan is pushing his bike up a hill. The bike is
accelerating at 15 m/s2. The force on it is 300
N. What is the mass of the bike?
 What do you know?
 What do you want to find out?
 Choose formula
 Substitute known values
 Calculate and simplify
Here is an example problem:
 Jorge is pushing a bookshelf across a room. If
the combined force is 300 N and the table is 60
kg, what is the acceleration of the bookshelf?
Section 2.3 Forces Act in Pairs
 Newton’s
third law relates action and
reaction forces.
 They key points to this law are that
when objects A and B interact:
 The force of A on B equals the force of B
on A
 The forces are in opposite direction
 In
action/reaction pairs either force can be
considered the action force or the reaction
force. (p. 58 for more examples)
 Imagine you are pinching shut a balloon filled
with air. You let go of the balloon. Think about
what usually happens.
○ What is the action force?
○ What is the reaction force?
 The
two forces occur simultaneously-at
the same time.
 Example: when you push down on a table, the
force from the table’s resistance increases
instantly to match your force.
 Action/reaction
force pairs occur when any
two objects interact, not just through
contact forces.
 Example: the pull of Earth on a falling baseball
is exactly that of the baseball pulling on Earth.
Earth is so much more massive; however, that
Earth’s acceleration from the pull is nearly
nothing. The acceleration of the baseball is
very noticeable.
 Action
and reaction forces are different
from balanced forces.
 Action and reaction forces are equal and
opposite.
○ Two forces acting in opposite directions (you go to
pick up your dog-you act against gravity, it acts
against you)
 Balanced forces act on a single object.
○ Two siblings arguing over a remote (both applying a
balanced force on a single object)

Newton’s three laws describe and predict
motion
 Newton’s laws work together to explain changes
in the motion of objects, such as a squid moving
forward when squirting water backward, or a bird
flying higher or changing direction.
 Newton’s laws are also useful in calculating how
objects move under conditions found in everyday
life.
 Scientists such as Albert Einstein have added to
our understanding of motion since Newton’s time.
○ Under certain conditions, such as extreme speed or
gravity, Newton’s laws need to be adjusted.
2.4 Forces Transfer Momentum
Before we begin learning about a new
concept, let’s review what we already
know about forces.
 http://science.discovery.com/interactives
/literacy/newton/newton.html
 If there were parts in this interactive you
did not understand, please arrange a
time to come meet with me. This is
review and we will not be going over it
again before the pop quiz and test.

 Objects in motion have momentum.
 Momentum can be though of as inertia
for moving objects.
 It is the tendency of a moving object to
keep moving at a constant velocity, and it
depends on the mass and velocity of the
object.
○ What do you predict would happen to an
object’s momentum if you increase the mass
of the object?
○ Imagine you are throwing a tennis ball against
a wall. Now imagine you are throwing a
bowling ball against a wall.
○ What happens when you increase the mass of
an object?
○ What do you predict happens to momentum
when you increase the velocity of an object?
○ Imagine you gently drop a grape on a piece of
paper towel held horizontal by another person.
Now imagine you increase the grape’s velocity
by throwing it against the paper towel.
○ What happens when you increase the velocity
of an object?
 Momentum=mass x velocity, or p= mv
○ What do you predict the units of momentum
are?
○ Determine the units for mass and velocity.
○ Combine the units to calculate momentum.
 Momentum, like velocity, is a vector, so it has
both size and direction.
 Adding the momentum of two objects is similar
to adding net forces.
○ Let’s try some example problems using momentum:
 What
is the momentum of a 1.5 kg ball
moving at 2 m/s?

What is the momentum of a 3 kg ball moving
with a velocity of 1 m/s?

What is the momentum of a .5 kg ball moving
at .5 m/s?

A force on an object changes the object’s
momentum.
 The change in momentum is equal to the force on
the object multiplied by the time over which the
force is acting.

Momentum can be transferred from one
object to another.
 Momentum is transferred during a collision.
○ Colliding objects exert equal and opposite forces on each
other while they are in contact.
○ The forces in the collision will change the velocity of each
object involved.
 What do you predict will happen in a situation where a tennis
ball and a bowling ball traveling toward each other collide?
 In a collision, the object with less mass has a greater change in
velocity.
 Momentum
is conserved.
 In any case where no outside forces are acting
on a system, the total momentum of the system
will not change, even if the momentum of
individual parts of the system changes.
 This conservation of momentum is most easily
seen in a collision.
 The forces acting are equal and opposite, and
they act over the same time period.
 Therefore, the change in momentum for two
colliding objects is equal and opposite, and the
total change in momentum is zero.
Section 3.1 Gravity is a force exerted by
masses.









Masses attract each other.
Gravity is the force objects exert on each other because of
their mass.
It attracts any two masses anywhere in the universe.
Greater mass results in greater force.
Greater distance results in smaller force.
The strength of the gravitational force is proportional to the
product of their masses divided by the distance between
them squared.
Gravitational acceleration is symbolized by g and equals 9.8
m/s2 at Earth’s surface.
Any object falling in a vacuum, no matter how massive, has
this acceleration.
The force of gravity, F, equals mg at Earth’s surface.
 This is because you can substitute g in for a according to
Newton’s first law, F=ma
Mass and Weight are not synonymous.
 Mass is the amount of matter something contains.
 Weight is the effect of gravity on the object.

BrainPop Gravity Video
 http://www.brainpop.com/science/motionsforcesan
dtime/







Gravity keeps objects in orbit.
An orbit is an elliptical path that one object takes
around another object.
An orbital path is the result of the speed of the orbiting
body and the gravitational pull between the two
objects.
The speed an object must have to escape the
gravitational pull of another body, such as a
spacecraft leaving a planet, is called escape velocity.
Speeds lower than the escape velocity will result in an
orbit.
A spacecraft and its contents in orbit are in free fall.
The environment is such that an astronaut can’t feel
gravity.
Section 4.1 Work is the use of
force to move an object.






Force is necessary to do work.
To do work on an object, a force must be applied to
the object, and the object must move in the direction
of the force.
For example, if the direction of force is away from a
person (you are pushing an object), the object will
move away.
If the direction of force is moving toward a person
(you are pulling an object), the object will move
toward him/her.
Work is done only by the component of the force that
acts in the same direction as the movement of the
object.
Work is done by force tht acts in the same direction of
motion as the object.
Work can be calculated by multiplying the force
applied to an object by the distance the object
moves while that force is being applied.
 W=Fd
 The standard unit of measurement of work is the
newton-meter, also called a joule.

Work BrainPop video
http://www.brainpop.com/science/motionsforcesandti
me/
 Let’s
try the following example together:
 How much work is done if a person lifts a
barbell weighing 450N to a height of 2m?
 What do you know?
 What do you want to find out?
 Formula
 Substitute in known values
 Calculate & Simplify
 Label with units
Try this one on your own:
 How much work is done if a person pushes a cart
weighing 1000N a distance of 10m?

Rearrange the work formula to figure this next one
out:
 How far will a 500N object travel, if the work to move
it is 2000 joules?

Objects that are moving can do work.
 The gravitational force of Earth does work on water
and other natural materials.
 People use moving objects to help them do work.

Games
Really fun ball drop & package delivery game!
(6):
 http://www.gamequarium.org/dir/Gamequarium/
Science/Forces_and_Motion/forces_and_motio
n2.html
 Friction and gravity Ramp experiment (8)

Section 5.2 Six simple machines
have many uses
 There
are six simple machines
 The lever and the inclined plane are the two
main types of simple machines.
 Other simple machines are based on these two.

http://www.harcourtschool.com/activity/science_up
_close/505/deploy/interface.html

http://www.brainpop.com/science/motionsforcesan
dtime/
○ A lever is a solid bar that rotates on a fixed point called a
fulcrum.
 There are three classes of levers based on the relative locations of
the input force, the output force, and the fulcrum. (see p. 155)
○ A wheel and axle is a wheel attached to a shaft.
 It acts like a rotating collection of levers.
 The input force can be applied to either part, which transfers force to
the other part.
 http://www.cosi.org/files/Flash/simpMach/sm1.swf
○ A pulley is a wheel with an axle and a grooved rim.
 A rope or a cable moves in the groove.
 Pulleys can be either fixed or movable.
 A combination of the two types is called a block and tackle.
○ An inclined plane is a sloping surface that supports the
weight of an object while the object moves from one level
to another.
○ http://www.cosi.org/files/Flash/simpMach/sm1.swf
○ A wedge has a thick end and a thin end.
 A wedge can be used to cut, split, pierce objects or to hold objects
together.
○ A screw is an inclined plane wrapped around a cylinder or
a cone to form a spiral.
 Screws can be used to hold things together or to raise or lower
objects.
 http://www.cosi.org/files/Flash/simpMach/sm1.swf
Mechanical Advantage

If a machine were 100 percent efficient, its ideal
mechanical advantage would be output force/input
force or
 MA= Fout/Fin
○ For an inclined plane, divide the length of the incline by the
height of the incline.
○ For a wheel and axle, divide the radius where the input force is
applied by the radius where the output force is applied.
○ For a lever, calculate this by dividing the distance from the input
force to the fulcrum by the distance from the output force to the
fulcrum.
○ For pulleys, the mechanical advantage is equal to the number of
ropes that support the weight.
○
http://www.cosi.org/files/Flash/simpMach/sm1.swf
 Calculate the mechanical advantage of a wheel and
axle with a wheel radius of 10 cm and an axle
radius of 2 cm.
○ What do you know?
○ What do you want to know?
○ Formula?
○ Substitute in known values.
○ Calculate & simplify
○ Label answer with units.
 Calculate the mechanical advantage of an inclined
plane with a height of 2 m and a length of 5 m.
 Super-Cool Simple Machine game!
 http://www.edheads.org/activities/odd_machine/index.htm