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Today’s Objectives-Learn what vector and scalar quantities are-Be able to distinguish between vector and scalar quantities-Learn if some common measurements (speed, weight…) arevector or scalar quantities-Learn the differences between speed and velocity-Learn the difference between displacement and distance
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What is a Scalar Quantity?Scalar quantities have only magnitude (=how much)Examples: • 10 meters • 2 liters • 20 kilometers per hour • 30 baht
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What is a Scalar Quantity?Scalar quantities have only magnitude (=how much)Examples: • 10 meters • 2 liters • 20 kilometers per hour • 30 baht Scalar 10 meters
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What is a Vector Quantity?Vector quantities have magnitude AND directionExamples: • 10 meters to the northeast (=displacement) • 100 kilometers and hour to the west (=velocity)
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What is a Vector Quantity?Vector quantities have magnitude AND directionExamples: • 10 meters to the northeast (=displacement) • 100 kilometers and hour to the west (=velocity) Vector 10 meters to the NE
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Why are Vectors Important?Can an asteroid’s path bedescribed using vectors?Yes! Asteroids havespeed AND a directionWe know whenmeteor showers arecoming because ofour understanding ofvectors
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PracticeLabel each quantity scalar or vector1. 80GB2. 20 meters per second to the north3. 20 degrees Celsius4. 25 centimeters5. 8 Newton force upward6. 35 seconds7. 1.3 billion people in China8. 80 kilograms
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AnswersLabel each quantity scalar or vector1. 80GB no direction = scalar2. 20 meters per second to the north has a magnitude and direction = vector3. 20 degrees Celsius no direction = scalar4. 25 centimeters no direction = scalar5. 8 Newton force upward magnitude and direction = vector6. 35 seconds no direction = scalar7. 1.3 billion people in China no direction = scalar8. 80 kilograms no direction = scalar
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Displacement vs DistanceDistance – how far something moved (meters)Displacement – how far, AND what direction something moved(meters to the NW) Displacement Distance VECTOR 18 km 18 m to the NW SCALAR
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Displacement vs Distance Distance – how far something moved (meters) Displacement – how far, AND what direction something moved (meters to the NW) Is the red or yellow line distance? DISTANCE Red is distance = how far moved Finish Yellow is displacement = how far and what direction DISPLACEMENT Displacement is always a straight line, and will always be shorter than distanceStart
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Displacement vs DistanceDistance – how far something moved (meters)Displacement – how far, AND what direction something moved(meters to the NW) Classwork: 1. A man walks around the outside of park and ends up in the same spot he started. What is his displacement? How much distance did he travel? 1km *His displacement is 0 *His distance traveled is 4 km 1km PARK 1km Start*Scalar or vector? 1km Finish
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SpeedSpeed is how fast an object is travelingSpeed = distance (in meters) time (in seconds)s=d tIt takes a swimmer 57.2 seconds to swim a distance of 100 m.What is the swimmer’s average speed?
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SpeedSpeed is how fast an object is travelingSpeed = distance (in meters) time (in seconds)s=d tIt takes a swimmer 57.2 seconds to swim a distance of 100 m.What is the swimmer’s average speed? s = d = 100m = 1.75 m/s t 57.2s
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SpeedSpeed is how fast an object is travelingSpeed = distance (in meters) time (in seconds)s=d tIt takes a swimmer 57.2 seconds to swim a distance of 100 m.What is the swimmer’s average speed? s = d = 100m = 1.75 m/s t 57.2s Scalar or vector??
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SpeedSpeed is how fast an object is travelingSpeed = distance (in meters) time (in seconds)s=d tIt takes a swimmer 57.2 seconds to swim a distance of 100 m.What is the swimmer’s average speed? No direction s = d = 100m = 1.75 m/s t 57.2s Scalar or vector?? Scalar
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VelocityVelocity is how fast an object is going, AND its directionVelocity = displacement (in meters) time (in seconds)Remember, displacement is distance AND directionIf you need to go from point A to point B in 10 minutes, whatvelocity do you need to get there on time? 3.7 km N A B W EVelocity = 3.7 km east = 0.37 km east/ minute 10 minutes S Scalar or vector? Vector because has direction
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Speed vs VelocitySpeed – how fast something is moving (m/s)Velocity – direction and speed of an object (displacement/s)
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Speed vs VelocitySpeed – how fast something is moving (m/s)Velocity – direction and speed of an object (displacement/s)If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that avector or scalar measurement??
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Speed vs VelocitySpeed – how fast something is moving (m/s)Velocity – direction and speed of an object (displacement/s)If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that avector or scalar measurement?? Speed has no direction = Scalar
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Speed vs VelocitySpeed – how fast something is moving (m/s)Velocity – direction and speed of an object (displacement/s)If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that avector or scalar measurement?? Speed has no direction = ScalarIf I say “I’m driving 85 kilometers and hour north toward ChiangMai”, is that a vector or scalar measurement??
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Speed vs VelocitySpeed – how fast something is moving (m/s)Velocity – direction and speed of an object (displacement/s)If I say “I’m driving 85 kilometers per hour in Chiang Mai”, is that avector or scalar measurement?? Speed has no direction = ScalarIf I say “I’m driving 85 kilometers and hour north toward ChiangMai”, is that a vector or scalar measurement?? Velocity has speedand direction = Vector
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Some Common MeasurementsMeasurement Example Vector or Scalar Speed 20 meters/second no direction = scalar Length 12m no direction = scalar Displacement 10m to the north direction = vector Volume 3 Liters no direction = scalar Area 23 meters squared no direction = scalar Mass 29 grams no direction = scalar Velocity 60km/h to the north direction = vector Force 56 Newtons down direction = vector
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Decide Scalar or VectorEnergy Scalar VectorLengthAreaVolumeSpeedDisplacement TimeVelocity TemperatureMassForce
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Remember…Scalar quantity has no directionVector quantity has directionDisplacement is distance with directionVelocity is speed with directionDon’t let these words scare you, they soundcomplicated, but they really aren’t.
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Complete Questions in NotebookDirections: Write vector or scalar 15-21 Complete the table1. 40 baht ______________2. 20 Joules ______________ Measurement Scalar or Vector3. 1.2 billion atoms ______________4. 28 degrees Celsius ______________ 15. Mass5. 8 km/hr west ______________6. 25 N down ______________ 16. Displacement7. 3 Liters ______________ 17. Area8. 23 km/hr in Bangkok______________9. 10 m west ______________ 18. Velocity10. 79 kg ______________ 19. ForceDirections: fill in11. Velocity is speed with __________. 20. Speed12. Displacement is direction and __________. 21. WeightA mountain bike rider followed the red line13. What was his displacement? 53km14. What was his distance traveled? Write questions and Finish answers in notebook 27km NE Start
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