Motion

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Motion
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A. Motion is when an object changes its position
relative to a reference point ( an object or
place is used to determine if an object changes
position).
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Displacement vs. distance 1. Distance how
far something moves 2. Displacement
the distance and direction of
an objects change in position from its
starting point
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B. Speed is the distance an object travels
per unit of time 1. The rate is any
change over time. 2. To calculate speed
take the distance traveled and divide it by the
time it took to travel that distance. Example
If I drove 100 km in 2 hours I would take 100
and divide it by 2. Answer would be 50 km per
hour. 100?2?50

d s t
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Equation

• V d t
• v (speed), d (distance), t (time)
• Variations
• to find d (distance) you use vt
• to find t (time) you use d v
• Pyramid

http//webs.rps205.com/teachers/tsaporiti/Unit1.ht
ml
d
Divide line
v
t
Multiply line
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• 3. Constant speed is the same
• speed throughout the trip.

4. Average speed is not the same throughout the
trip add the total distance and divide by the
total time. Speed total Distance / total Time
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5. Instantaneous speed is speed at any given
moment.
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Graphing speed
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D. Velocity is Speed in a given
direction Velocity can change even if
speed is constant as long
as direction changes
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II . Acceleration A. The rate of change
of velocity 1. a speeding up 2. -a
slowing down 3. A change in speed or direction
is called acceleration.
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B. Calculating acceleration 1. a (vf vi) /
t or a ? v / t 2. (vf vi) 3.
Units are m/s/s
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Example constant speed acceleration
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Graphing Acceleration
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Force
D. Forces 1. A force is a pull or push.
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Balanced and Unbalanced Forces

• When an object moves at a constant speed or is
  stationary, the forces are balanced.
• Balanced forces will not change an objects
  motion.

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• Balanced and Unbalanced Forces
• There generally is no motion when you lean
  against a wall.
• The force you exert by leaning is less than the
  capacity of
• the wall to support you or push back.
• This type of force is called a balanced force
• What if you could push against the wall with
• more force than it was able to withstand?
• The wall would likely fall over or you would push
  
• your hands through it.
• This is an example of an unbalanced force or a
  net force.

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Unbalanced forces
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Law of Inertia

• 1st Law An object at rest will stay at rest,
  and an object in motion will stay in motion at
  constant velocity, unless acted upon by an
  unbalanced force.
• Unbalanced forces acting on an object will cause
  it to start moving, stop moving or change
  direction.

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http//www.westone.wa.gov.au/k-12lrcd/learning_are
as/integ_science/IS1D/content/001_extreme_sports/p
age_05.htm
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Inertiaan objects resistance to a change of
motion.

• All matter has mass.
• Inertia is dependent
• on the amount of mass an object has.

• The greater the mass of an object the greater the
  objects inertia.
• The more difficult to start or stop an object.

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Inertia

• If the car is stopped suddenly the passenger will
  continue moving forward.
• The passenger has inertia and thats why we wear
  seat belts.

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Inertia
Why didnt the penny move with the index card?
The pennys inertia(doesnt move unless acted on
by an unbalanced force.)
What happens when you slowly flick the card?
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2nd Law

• AccelerationForce equals mass multiplied by
  acceleration
• F ma
• Force is any push or pull that can affect motion
• Mass in kg, acceleration in m/s2
• Newtons 1N 1kgm/s2
• And can be rewritten as
• Acceleration equals Force divided by mass.

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Newtons 2nd law

• What is the force applied by a mass of 2 kg with
  an acceleration of 6 m/s2?
• 6 N
• 3 kg?m/s
• 12 kg?m/s2

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• What is the acceleration of a mass of 6 kg
  applying a force of 24 N?
• 4 m/s2
• 144 m/s2
• 0.25 m/s2

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• Since both vans have the same engine, both have
  an applied force on them that is equal.
• The truck with the large inertia will have a
  small acceleration, while the truck with less
  inertia will have greater acceleration. 
• inertia is what resists a change in velocity. 
• The more inertia (more mass), the less the change
  in velocity there will be.  The greater the mass,
  the smaller the acceleration.  

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• Surfaces can appear smooth, but microscopically
  you can observe peaks and valleys which cause the
  friction.

• http//www.teachertube.com/viewVideo.php?video_id
  539

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Microscopic look at a smooth surface
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Friction is a force that
acts in a direction opposite to the direction of
an objects motion.
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Friction is a force that affects motion.

• There are four main types of friction
• Sliding friction ice skating
• Rolling friction bowling
• Fluid friction (air or liquid) air or water
  resistance
• Static friction initial friction when moving an
  object

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Gravity pulls objects toward one another
Weight is equal to the force of gravity on an
object on the surface of a planet.
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Newtons Third Law

• For every action, there is always an opposite and
  equal reaction.
• .  The reaction, or motion, of the rocket away
  from the launch pad is equal to and ?opposite
  from the thrust of the engine or nozzle. 

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http//teachertech.rice.edu/Participants/louviere/
Newton/law1.html
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More review

• http//teachertube.com/viewVideo.php?video_id539