Speed and Velocity

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Speed and Velocity

• 11.2 Page 332-337

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SPEED

• Speed is the RATIO of the distance an object
  moves over the amount of time the object moves
• SI Units Meters per second (m/s)

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Average Speed

• Average speed is computed for the entire duration
  of a trip, and instantaneous speed is measured at
  a particular instant.
• Average speed Driving to the mall 25 mi/hr, hit
  stop lights, freeway 55 mi/hr, off ramp 25 mi/hr,
  stop lights, slow in the parking lot.
• Instantaneous speed When police officers tag
  cars for speeding they are measuring the speed at
  that moment in time

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Average Speed

• Average Speed total distance
  total time
• v d
• t
• Pg 333 Example
• You travel 35 kilometers in 0.4 hours and then
  you travel 53 kilometers in 0.6 hours. What is
  your average speed for the entire trip?
• Total distance ? 35 km 53 km ? 88km
• Total time 0.4 h 0.6 h 1.0 h
• ? 88 km ? 88 km/hr
• 1.0 h

or
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Instantaneous Speed

• The rate at which an object is moving at a given
  moment in time
• When police officers tag cars for speeding they
  are measuring the speed at that moment in time

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Graphing Motion

• Slope of a line on a distance-time graph is the
  objects speed

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Distance-Time Graph

• Faster the speed -- the steeper the line
• Curved line -- the speed is increasing or
  decreasing
• Straight line -- constant speed

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Velocity

• The speed and direction in which an object is
  moving
• Speed in a given direction
• Description of Speed AND direction of motion

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Combining Velocities

• Combine velocities using vector addition. Two or
  more velocities add by vector addition
• Add velocities in the same direction
• Subtract velocities in opposite directions

Current 3 m/s
?
Swimmer 2 m/s
Total velocity of swimmer 5 m/s
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Combining velocities that are not in a straight
line

• You can determine the resultant velocity of the
  boat relative to the riverbank by measuring from
  the tail of one vector to the head of the other

11
QUESTOINS??

• Pg 333 - Extra practice answer the practice
  problems
• Homework Worksheet 11.2 - Speed and Velocity