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Notes – Representing Motion
Laws of Motion
• Isaac Newton – 1686 –
English scientist
discovered the three
laws of motion
• Motion – The change in
position when
compared to a
reference point
– Reference point – A
place or object used to
determine if something
is in motion
Laws of Motion
• Isaac Newton – 1686 –
English scientist
discovered the three
laws of motion
• Motion – The change in
position when
compared to a
reference point
– Reference point – A
place or object used to
determine if something
is in motion
Laws of Motion
• Isaac Newton – 1686 –
English scientist
discovered the three
laws of motion
• Motion – The change in
position when
compared to a
reference point
– Reference point – A
place or object used to
determine if something
is in motion
Laws of Motion
• Isaac Newton – 1686 –
English scientist
discovered the three
laws of motion
• Motion – The change in
position when
compared to a
reference point
– Reference point – A
place or object used to
determine if something
is in motion
• Are we in motion?
• 1 day =
• Earth circumference =
• Distance / Time =
• Earth’s orbit around sun=
• Time for orbit =
• Distance/Time =
Laws of Motion
• Isaac Newton – 1686 –
English scientist
discovered the three
laws of motion
• Motion – The change in
position when
compared to a
reference point
– Reference point – A
place or object used to
determine if something
is in motion
• Are we in motion?
• 1 day =
• Earth circumference =
• Distance / Time =
• Earth’s orbit around sun=
• Time for orbit =
• Distance/Time =
1st Law of Motion
• 1st Law : Bodies at rest
stay at rest, bodies in
motion stay in motion
unless acted upon by
another force. Law of
Inertia.
• Inertia – Causes
resistance to change in
motion
1st Law of Motion
• Law of Inertia.
• Inertia – Causes
resistance to change in
motion
– Friction – A force that
slows down motion.
– 1st Law examples: It
takes force to move an
object. A hockey puck
slides in a straight line
across ice. Gravity keeps
things stationary on
earth
1st Law of Motion
• Law of Inertia.
• Inertia – Causes
resistance to change in
motion
– Friction – A force that
slows down motion.
– 1st Law examples: It
takes force to move an
object. A hockey puck
slides in a straight line
across ice. Gravity keeps
things stationary on
earth
1st Law of Motion
• Law of Inertia.
• Inertia – Causes
resistance to change in
motion
– Friction – A force that
slows down motion.
– 1st Law examples: It
takes force to move an
object. A hockey puck
slides in a straight line
across ice. Gravity keeps
things stationary on
earth
Motion
• Motion diagram –
Shows the position of a
moving object at equal
time intervals
• Particle model –
replaces objects with
single points located at
a central point on the
object
Motion
• Motion diagram –
Shows the position of a
moving object at equal
time intervals
• Particle model –
replaces objects with
single points located at
a central point on the
object
Motion
• Motion diagram –
Shows the position of a
moving object at equal
time intervals
• Particle model –
replaces objects with
single points located at
a central point on the
object
Motion
• Coordinate system
Origin = all points zero (0)
= position
[------ distance -------]
Magnitude = quantities of size
Vector = Magnitude and
direction
direction
[------magnitude ----]
Scalar = no direction ( 5m)
Motion
• Coordinate system
Origin = all points zero (0)
= position
[------ distance -------]
Magnitude = quantities of size
Vector = Magnitude and
direction
direction
[------magnitude ----]
Scalar = no direction ( 5m)
Position-time graph
• Time interval
t = tf - ti
i = initial f = final
Displacement = change
in position = x
x = xf - x i
Position-time graph
• Time interval
t = tf - ti
i = initial f = final
Displacement = change
in position = x
x = xf - x i
Position-time graph
• Time interval
t = tf - ti
i = initial f = final
Displacement = change
in position = x
x = xf - x i
Position-time graph
• Time interval
t = tf - ti
i = initial f = final
Displacement = change
in position = x
x = xf - x i
Position-time graph
• Time interval
t = tf - ti
i = initial f = final
Displacement = change
in position = x
x = xf - x i
Speed and Velocity
Speed is equal to distance
over time.
• S=D/t
• If you travel 10 meters
in 5 seconds, your
speed is 10 m / 5 s =
• 2 m/s meters/second
Velocity is equal to speed
and direction
• 2 m/s east
Vector – shows magnitude and direction
Velocity
• Average velocity =
v=
x = xf - xi
t
tf - ti
= vertical coordinates
horizontal coordinates
X = instantaneous position
x
t
Absolute value of velocity =
speed
Slope =
Avg. speed + direction = velocity
V = instantaneous velocity
Velocity
• Straight line equation
• y = mx + b
• y = quantity plotted on vertical
axis
• x = quantity plotted on horizontal
axis
• m = line’s slope
• b = lines y-intercept
xi = initial position
y = x (position)
x = t (time)
Velocity
•
•
•
•
•
•
Straight line equation
y = mx + b
y = quantity plotted on vertical axis
x = quantity plotted on horizontal axis
m = line’s slope
b = lines y-intercept
xi = initial position
y = x (position)
x = t (time)
(0, 20) (4,0)
y = mx + b
m=
20-0 = - 5.0 m/s
0-4
y = (-5.0 m/s)x + 20.0 m
x = vt + xi
Velocity
• xi = initial position
y = x (position)
x = t (time)
(0, 20) (4,0)
y = mx + b
m=
20-0 = - 5.0 m/s
0-4
y = (-5.0 m/s)x + 20.0 m
x = vt + xi
x = (-5.0 m/s)t + 20.0 m
2nd Law of Motion
• Acceleration of an
object depends on the
amount of mass and the
size of the force.
• Acceleration = change
in speed or velocity
over time. It could be
speeding up, slowing
down, or changing
directions
2nd Law of Motion
• Acceleration of an
object depends on the
amount of mass and the
size of the force.
• Acceleration – change
in speed or velocity
over time. It could be
speeding up, slowing
down, or changing
directions
2nd Law of Motion
• The acceleration of an
object is directly
proportional to the
force and inversely
proportional to the
mass
• a = F / m
acceleration = Force / mass
Large force = large acceleration
Large mass = small acceleration
2nd Law of Motion
• The acceleration of an
object is directly
proportional to the
force and inversely
proportional to the
mass
• a = F / m
Large force + small mass = high acceleration
small force + large mass = low acceleration
acceleration = Force / mass
Large force = large acceleration
Large mass = small acceleration
Larger force = higher acceleration
2nd Law of Motion
• Falling objects – All
objects fall at the
same rate
• Large mass
small mass
Little force
big acceleration
Big Force
little acceleration
2nd Law of Motion
• Falling objects – All
objects fall at the
same rate
• Large mass
small mass
Little force
big acceleration
Big Force
little acceleration
2nd Law of Motion
• Air resistance– Air
friction slows down
falling objects
• In a vacuum (no air) a
feather would fall at
the same rate as a
bowling ball
3rd Law of Motion
• If one object exerts a
force on another object,
then the second object
exerts a force of equal
strength in the opposite
direction.
• For every action (force)
there is an equal and
opposite reaction
(force)
3rd Law of Motion
• If one object exerts a
force on another object,
then the second object
exerts a force of equal
strength in the opposite
direction.
• For every action (force)
there is an equal and
opposite reaction
(force)
3rd Law of Motion
• For every action (force)
there is an equal and
opposite reaction
(force)
• Ex: Recoiling of a fired
gun, a balloon travels in
the opposite direction
of air flow
3rd Law of Motion
• Momentum - An
object’s mass multiplied
by its velocity
• Conservation of
Momentum – When
two or more objects
collide, the total
momentum of the
object is the same after
as before
• M1V1 = M2V2
1 kg x 10 m/s = 5 kg x ___ m/s
3rd Law of Motion
• Conservation of
Momentum – When
two or more objects
collide, the total
momentum of the
object is the same after
as before
• Angular momentum –
Velocity of rotation
increases as the
distance from the
center becomes smaller
3rd Law of Motion
• Conservation of
Momentum – When
two or more objects
collide, the total
momentum of the
object is the same after
as before
• Angular momentum –
Velocity of rotation
increases as the
distance from the
center becomes smaller
Force
• Force - Any push or pull
acting on an object
• Measured in Newtons
(N)
Fundamental Forces
• 1) Gravity – Causes an
attraction between the
mass of objects and
produces weight
• 2) Electromagnetic Causes an attraction
between positive and
negative charges
• 3) Nuclear – Strongest
fundamental force. It
holds protons and
neutrons together in the
nucleus of atoms
Fundamental Forces
• 1) Gravity – Causes an
attraction between the
mass of objects and
produces weight
• 2) Electromagnetic Causes an attraction
between positive and
negative charges
• 3) Nuclear – Strongest
fundamental force. It
holds protons and
neutrons together in the
nucleus of atoms
Fundamental Forces
• 1) Gravity – Causes an
attraction between the
mass of objects and
produces weight
• 2) Electromagnetic Causes an attraction
between positive and
negative charges
• 3) Nuclear – Strongest
fundamental force. It
holds protons and
neutrons together in the
nucleus of atoms
Energy
• Energy is the ability to
do work
• Energy enables forces
to move objects
2 main types
• Potential
• Kinetic
1) Potential Energy
• Potential energy is
stored in an object as a
result of its position
• Examples: Book on a
shelf, rock on a cliff,
stretched rubber band
2) Kinetic Energy
• Kinetic energy is the
energy of motion and
moving objects. It is
the energy in falling or
moving objects
• Ex: Pendulum – Bob on
a string. Changes from
potential to kinetic to
potential
2) Kinetic Energy
• Kinetic energy is the
energy of motion and
moving objects. It is
the energy in falling or
moving objects
• Ex: Pendulum – Bob on
a string. Changes from
potential to kinetic to
potential
Forms of Energy
• 1) Mechanical – energy
of motion or position
(machines)
• 2) Chemical – Changes
one kind of matter to
another.
Battery electricity
Food
motion and heat
Forms of Energy
• 1) Mechanical – energy
of motion or position
(machines)
• 2) Chemical – Changes
one kind of matter to
another.
Battery electricity
Food
motion and heat
Forms of Energy
• 3) Heat – Moving
molecules and changes
in temperature
• 4) Electric – Flow of
electrons
• 5) Electromagnetic –
Rays which spread out
and pass through space
Ex: radio, light, UV,
infrared
Forms of Energy
• 3) Heat – Moving
molecules and changes
in temperature
• 4) Electric – Flow of
electrons
• 5) Electromagnetic –
Rays which spread out
and pass through space
Ex: radio, light, UV,
infrared
Forms of Energy
• 3) Heat – Moving
molecules and changes
in temperature
• 4) Electric – Flow of
electrons
• 5) Electromagnetic –
Rays which spread out
and pass through space
Ex: radio, light, UV,
infrared
Forms of Energy
• 6) Nuclear – Changes
in nuclei of atoms.
Most concentrated
form .
Ex: Atomic power plants