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Unit 6: Motion and Forces 2015 Stevens
1
Unit 6: Motion and Forces VOCABULARY:
Term Definition Equation (if applicable) or
example
Motion
Speed
Distance
How much ground an object has covered
during its motion; how far apart two points
are
Velocity
Frame of
reference
Acceleration
Vector
Force
Net Force
Inertia
Newton’s 1st
Law of Motion
(Law of Inertia)
objects at rest remain at rest, and objects in
motion remain in motion with the same
velocity, unless acted upon by an
unbalanced force
Newton’s 2nd
Law of Motion
the acceleration of an object increases with
increased force and decreases with
increased mass
Newton’s 3rd
Law of Motion
Unit 6: Motion and Forces 2015 Stevens
2
Gravitational
Force
Section 1:
Key Ideas:
Analyze the motion of an object in terms of its position, velocity and acceleration as functions
of time
Solve problems involving distance, velocity, speed and acceleration
Create and interpret graphs
Vocabulary:
Motion - Displacement
Speed - Acceleration
Velocity - Vector
Distance
Frame of Reference
Motion
_______________________________________________________________________
_______________________________________________________________________
relies on a frame of reference or something assumed to be stationary
_______________________________________________________________________
o i.e. – you may be stationary as you sit in your seat, but you are moving 30 km/sec (≈19
mi/sec) relative to the Sun
Frame of Reference (Reference Point)
_____________________________________________________________________________
none are truly stationary relative to all others – what is not moving in one is moving in another
Task:
o Using your body as the frame of reference, describe your classmate’s motion as s/he walks to
the classroom door. How does your frame of reference impact your description compared to
that of others? __________________________________
__________________________________________________________________
How does frame of reference explain why people thought the Earth was in the center of all
celestial bodies? _________________________________________
__________________________________________________________________
Speed
Unit 6: Motion and Forces 2015 Stevens
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___________________________________________________________________________
a measure of how fast something moves, or the distance it moves, in a given amount of time
Formula: s = d (distance)
t (time)
typically expressed in units of m/s
is considered _______________ when taking into account the total distance covered and the total
time of travel
is considered __________________when it does not change
is considered _______________________ when it represents a specific instant in time
What is the ball’s speed? ___________________________________________________
Practice problems – Speed:
1. If you walk for 1.5 hours and travel 7.5 km, what is your average speed?
2. Calculate the speed of a bee that flies 22 meters in 2 seconds.
Draw the Speed-Distance-Time Triangle
Draw the distance time graph:
1. What is the speed from A – B? ________________________________________
2. What is the speed from B-C? __________________________________________
3. What is the speed from C-D? __________________________________________
4. What is the students average speed? _____________________________________
Unit 6: Motion and Forces 2015 Stevens
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Underneath each graph, describe what’s happening?
Thought question: Two birds perched directly next to each other, leave the same tree at the same time. They
both fly at 10 km/h for one hour, 15 km/h for 30 minutes, and 5 km/h for one hour. Why don’t they end up
at the same destination? ______________________________________
______________________________________________________________________________
Velocity
_______________________________________________________________________
_______________________________________________________________________
is considered ____________________when speed and direction do not change
changes as ________________________________________________ changes
is a vector
can be combined
o Example
If you are walking at a rate of 1.5 m/s up the aisle of an airplane that is traveling north
at a rate of 246 m/s, your velocity would actually be 247.5 m/s north
What is the formula for velocity? What is this similar to? _________________________
________________________________________________________________________
Unit 6: Motion and Forces 2015 Stevens
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Vector:
______________________________________________________________________________
drawn as an arrow which shows direction and magnitude (length of arrow)
o consists of two parts: tail and head (draw an example)
Combining Vectors:
can be combined/added
What is the total velocity for each of the people/animals on the conveyor belt?
_____________________ ________________________ ___________________
Acceleration:
____________________________________________________________________________
is a vector
occurs when something is speeding up (+), slowing down (-), or changing direction
Formula: a = vf – vi (where vf is final velocity, and vi is initial velocity)
t(time)
typically expressed in units of m/s2
is always changing when traveling in a circle – centripetal
1. Is the ball accelerating? ________________________________________________
2. Describe the car’s acceleration: ______________________________________________
________________________________________________________________________
Unit 6: Motion and Forces 2015 Stevens
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3. What if I am traveling in my car at 60mph North constantly? What would my acceleration be?
__________________________________________________________
Practice Problems – Acceleration:
1. Tina starts riding her bike down a hill with a velocity of 2 m/s. After six seconds, her velocity is
14 m/s. What is Tina’s acceleration?
2. A motorcyclist goes from 35 m/s to 20 m/s in five seconds. What was his acceleration?
Momentum:
________________________________________________________________________________
is a vector
the product of an object’s mass and velocity
Formula: p=mv (p is momentum, m=mass, v=velocity)
typically expressed in units of kg·m/s
_________________________________________________________________________________
makes an object harder to stop or change direction as it increases
can be transferred
is conserved
Practice Problems – Momentum:
1. What is the momentum of a 7.3 kg bowling ball moving at 8.9 m/s?
Unit 6: Motion and Forces 2015 Stevens
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2. At a velocity of 8.5 m/s, Tim moves down a hill on an inner tube. If his mass is 59 kg, how much
momentum does he have?
Practice:
A helicopters speed increases from 25 m/s to 60m/s in 5 seconds. What is the acceleration of this
helicopter?
How far will you travel if you run for 10 minutes at 2.0m/s?
How much time would it take for the sound of thunder to travel 1,500 meters if sound travels at a
speed of 330m/s?
At a velocity of 10 m/s NE, Sadie moves down a mountain on her snowboard. If her momentum is
460 kg·m/s, what is her mass?
Section 2: Forces and Newton’s 3 Laws of Motion
Key Ideas
Interpret and Apply Newton’s 3 Laws of Motion
Vocabulary
Inertia - Force
1st Law - Net force
2nd
Law - Applied force
3rd
Law - Normal force
Friction - Air Resistance
Tension - Spring
Force:
____________________________________________________________________________
typically measured in Newtons (kg•m/s2)
Unit 6: Motion and Forces 2015 Stevens
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is a vector
can be combined to predict motion net force
Net force: ____________________________________________________________________
Types of Forces:
Contact Forces
o Applied
o Normal
o Friction
o Air Resistance
o Tension
o Spring
Applied Force:
any push or pull on an object created from another source (person, animal, another object, etc.)
Normal Force:
the support force exerted on an object directly related to weight (gravity)
consequence of Newton’s 3rd
Law
_____________________________________________________________________________
Draw and label the pictures
Friction:
exerted by a surface as an object moves across it or attempts to move across it
___________________________________________________________________________
depends on the type of surfaces and the normal force (weight)
Non-Contact Forces
o Gravity
o Electromagnetic
Unit 6: Motion and Forces 2015 Stevens
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Air Resistance:
____________________________________________________________________________
acts upon objects as they travel through the air
___________________________________________________________________________
most noticeable for objects traveling at fast speeds
Tension:
force that is transmitted through a string, rope, cable or wire when it is _______________ tight by
forces acting from opposite ends
directed along the length of the wire and ______________ equally on the objects on the opposite
ends of the wire
Spring:
________________________________________________________________________________
for most springs, the magnitude of the force is directly proportional to the amount of stretch or
compression of the spring
Gravity:
_____________________________________________________________________________
factors:
distance – increased distance less gravitational pull or vice versa
mass – increased mass more gravitational pull or vice versa
Why does the force of gravity have more of an impact on holding our solar system together
compared to holding the parts of an atom together? _________________
___________________________________________________________________
Electromagnetic Force:
Unit 6: Motion and Forces 2015 Stevens
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force that moving charges exert on one another
results from the repulsion of like charges and the attraction of opposites
Vector Review:
a quantity that has both direction and magnitude (size)
drawn as an arrow which shows direction and magnitude (length of arrow)
o consists of two parts: tail and head
Draw the vectors. Then describe the direction and relative magnitude of each ball based on the
vector.
Combining Vectors Review:
can be combined/added to help determine net force
o the overall force acting on an object when all of the forces acting on it are combined
o Draw the picture and determine the net force.
Free Body Diagrams:
visuals that help show net force
o use a square and draw all forces acting on the object.
o remember size and direction of vector arrows are important!
Unit 6: Motion and Forces 2015 Stevens
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o Draw the diagram and determine the net force.
Determine the net force:
Net force: __________________________ Net force:_____________________
Newton’s Laws of Motion:
Newton’s 1st Law of Law of Inertia:
objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless
acted upon by an unbalanced force
also considered the Law of Inertia
How is this illustrated when riding in a car? Can you think of other experiences where this is
illustrated? _________________________________________________________
________________________________________________________________________
Fgrav
= 10 N
Ffric
= 5 N
Fnorm
= 10 N
Fapp
= 15 N
Unit 6: Motion and Forces 2015 Stevens
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Inertia:
the resistance of an object to a change in the speed or the direction of its motion
________________________________________________________________________
Which has more inertia: a car or a person? Why? ____________________________
________________________________________________________________________
Newton’s 2nd
Law of Motion:
the acceleration of an object increases with increased force and decreases with increased mass
_________________________________________________________________________________
Formula: F = ma (or a = F/m)
Practice Problems – 2nd
Law:
1. What net force is needed to accelerate a 24 kg dogsled to a rate of 3 m/s2?
2. A 1.5 kg object accelerates across a smooth table at a rate of 0.5 m/s2? What is the unbalanced
force applied to it?
Newton’s 3rd
Law of Motion:
states that every time one object exerts a force on another object, the second object exerts a force
that is equal in size and opposite in direction back on the first object
Can you think of any experiences/examples where this is illustrated? ________________
________________________________________________________________________
Section 3: Gravitational Force
Key Ideas
Unit 6: Motion and Forces 2015 Stevens
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o Explore how the gravitational force between two objects depends on their masses and the
distance between them.
Vocabulary
o Gravity
o Gravitational Constant
Law of Universal Gravitation:
Where:
Fg = Force of Gravity
G = the gravitational constant (6.67 x 10-11
N *m2/kg
2)
M1= Mass of object 1
M2 = Mass of object 2
d = distance between two objects
Gravity ____________________________________________________________________!!!!!!
Unit 6: Motion and Forces 2015 Stevens
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SECTION 3:
Key Ideas:
• What are Synthesis (creating)
• Decomposition (separating)
Unit 6: Motion and Forces 2015 Stevens
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• Combustion (burning)
• Displacement/Replacement (switching)
SYNTHESIS (CREATING)
• ________________________________________________________________________
• Ex: Synthesis of Carbon Dioxide
2CO(g) + O2(g) → 2CO2(g)
DECOMPOSITION (SEPARATING)
• _______________________________________________________________________
• Ex: Electrolysis of water to make hydrogen and oxygen
• 2 H2O ---> 2 H2 + O2
COMBUSTION (BURNING)
• ______________________________________________________________________
• Oxygen reacts with another element or compound to form water (H2O), carbon dioxide (CO2) and
heat
• _______________________________________________________________________
Unit 6: Motion and Forces 2015 Stevens
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DISPLACEMENT/REPLACEMENT (SWITCHING)
• Two types: Single replacement and double replacement
• Single replacement (substitution):
___________________________________________________________________________
_________________________________________________________
• Ex: Zn + 2 HCl → ZnCl2 + H2
• Ex:
• Double Replacement: _______________________________________________
__________________________________________________________________
• Ex: AgNO3 + HCl → AgCl + HNO3
• Ex: Fe2O3 + HCl → FeCl3 + H2O
CHEMICAL VS NUCLEAR RXN:
Chemical Reaction
• Atoms are rearranged, and chemical
bonds are broken and reformed
• New substance is formed
C6H12O6 + 6O2 6CO2 + 6H2O + energy
(respiration)
Nuclear Reaction
• __________________________________
• Involves at least two nuclei, where one
has to have all its electrons removed, by
bringing it to very high temperatures. Why
must the electrons be removed?
• A neutron is then “slammed” into another
nucleus, causing the nucleus to break
apart (fission) or combine to create a new
nucleus (fusion)