Linear Motion

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Linear Motion
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Time

• Time a useful measurement of changes in motion
  or events all or part of the past, present, and
  future.
• For most cases time is measured in seconds.

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Displacement
http//hypertextbook.com/physics/mechanics/displac
ement/

• Displacement change in position (includes
  direction!)
• Distance- total path length traveled in moving
  from one location to another

Determine the distance the displacement in the
diagram
Total distance is 11 meters, but displacement is
3 meters
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Positive or Negative can be used to show
direction!

• Usually symbolizes up, right, north, east,
  forward
• - Usually symbolizes down, left, south, west,
  backwards

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Motion a change in position

• Speed - how much distance an object covers per
  unit time
• distance is commonly measured in meters (m)
• time is commonly measured in seconds (s)

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Equation

• v average speed
• d distance
• t time

v velocity and is used to represent average
speed in this basic equation
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Unit of Measure

• Since distance is measured in meters (m) and time
  is measured in seconds (s) we can determine the
  units for speed...
• distance time in units would be m s or m/s
• The unit for speed is therefore m/s or meters per
  second!

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Speed VS. Velocity

• Velocity is your speed and the direction you are
  moving in.
• velocity speed direction
• ex 45 m/s, North
• 10 m/s, towards the mall

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The shape of a Position (distance) VS. Time Graph

• Constant Velocity
  (positive)
• Changing Velocity
  (positive)
• acceleration

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Position vs. time Graph
Distance (m)

• Constant positive velocity to top of point,
  moving AWAY from the origin
• and then constant negative velocity as the object
  moves towards the origin

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Distance vs time graph

• A-B constant positive velocity
• B-C increasing velocity and decreasing velocity
• D at rest D-E increasing velocity

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• We will begin with the next slide in a day or two

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Which of the above graphs best fits the situation
to the right?
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Motion Graphs

• Motion Graphs

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• Acceleration- rate of change in velocity

1. Which car (red, green, or blue) experiences the
   greatest acceleration?
2. Consider the position-time graph at the right.
   Each one of the three lines on the position-time
   graph corresponds to the motion of one of the
   three cars in the graphic above. Match the
   appropriate line to the particular color of car.

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Graph Interpretation

• 1.Describe the motion based on the graph.
• 2. What WORD best describes the slope of the
  graph?

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VERTICAL MOTION!
Whats the difference? Why does the leaf float
but yet the water drop falls?

• What do you know about falling objects?
• Do heavier objects fall faster than lighter
  objects?
• Effect of Mass on Falling Object

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BUT WAIT.

• All things dont fall at the same speed?
• WHY

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Do heavier objects fall faster?

• Feather Hammer On Moon!

No air resistance
Real scenario
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http//visual.physics.tamu.edu/vp218/LabManual/Fig
ure02_22.jpg
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Free Fall, Acceleration due to Gravity

• The position of the free-falling object at
  regular time intervals, every 0.1 second, is
  shown.
• The distance which the ball travels every
  interval of time increases.

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Free Fall

• Motion under the influence of gravity only
• The force of gravity accelerates ALL objects
  towards earth at 9.81m/s²

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oopsnow what?

• What happens as Wile E. Coyote falls?
• time
• speed
• acceleration
• distance

http//www.studyphysics.ca/newnotes/20/unit02_circ
ulargravitation/chp07_2d/lesson26.htm
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The FALL of Wile E.Coyote at 1 s. intervals
Time (s) Speed (m/s) Accel. (m/s2) Dist. (m)
0
1
2
3
4
5
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Imagine throwing a ball straight up into the air
with an initial velocity of 40 m/s and it returns
to your hand

• Diagram the situation.
• Describe the motion at each second.
• In other words
• is the speed increasing or decreasing?
• is the ball moving up or down?
• Estimate the velocity and acceleration at each
  second!
• Up Down