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Quiz. Distance Displacement, Velocity -Calculating Displacement (2 methods) Instantaneous and Average Velocity D-t and V-t graphs (words and graphs) Measurement and Sig Figs. Distance, Displacement and Position.
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Quiz • Distance Displacement, Velocity -Calculating Displacement (2 methods) • Instantaneous and Average Velocity • D-t and V-t graphs (words and graphs) • Measurement and Sig Figs
www.wikipremed.com/image.php?img=010101_68zzzz101450_323px-Distancedisplacement.svg_68.jpg&image_id=101450www.wikipremed.com/image.php?img=010101_68zzzz101450_323px-Distancedisplacement.svg_68.jpg&image_id=101450
Distance, Position, Displacement • DistanceTravelled = ground you’ve covered (pedometer) or total path length • You travel 402 meters when you walk around the track. • You travel 401 miles of road between Marblehead and Quebec. • You drive 3.0 miles when you go to school.” • You rise 15 feet when you take the elevator.
Distance, Position, Displacement • Position = where you are (mile marker) • 2 m in front of the whiteboard • At x = 2 m • At x = -2 m • 2 meters away from the whiteboard • At x = 2 m, where x = 0 m is the whiteboard
Distance, Position, Displacement • Displacement (Δx = x2 – x1) = change in position (snapshots) • 3 seats to the left • 3 m to the left • Δx = -3 m • 3 m in the negative direction • Starting at x= 9 m and ending at x = 6 m • Starting at x1 = 4 m and ending at x2 = 1 m • Starting at x0 = 1 m and ending at x = -2 m
Method #1 Displacement is area under V-t graph http://www.physicsclassroom.com/calcpad/1dkin
Method #2 Displacement is change in position on D-t graph Displacement (Δx = x2 – x1) = change in position
Instantaneous Velocity • Instantaneous velocity= how fast you are going AND your direction • -20 miles per hour • +4 m/s • -3.2 furlong/day • +8 knots • -45.6 mph • -32.5 in./year • +9 nm/ms
Average Velocity • Average Velocity = Displacement / Time • 20 miles per hour west • -4 m/s • 3.2 furlong/day towards Boston • 8 knots away from the shore • 45.6 mph ENE • 32.5 in./year up • 9 nm/s towards the ocean
But How to Find the average velocity over some time interval?
D-T Graphs (Lab 2) • Linear D-t Graph = Constant Velocity • Curvy D-t Graph = Changing Velocity • Faster = Steeper Slope • Slower = Less Steep Slope • Towards = Negative Slope • Away = Positive Slope
V-T graphs (Lab 3) • Constant Velocity = Horizontal V-T Graph • Changing Velocity = Diagonal V-T Graph • Faster = Larger Velocity • Slower = Smaller Velocity • Towards = Negative Velocity (Below Time Axis) • Away = Positive Velocity (Above Time Axis)
http://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htmhttp://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htm
http://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htmhttp://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htm
http://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htmhttp://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htm
http://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htmhttp://schools.cbe.ab.ca/b858/dept/sci/teacher/zubot/Phys20notes/Chapter2/3chapter2/3chapter2A.htm
What are the following? Distance Travelled, Position, or Displacement? • 5 meters up • 30 meters to go from A208 to D216 • In Mr. Forcier’s classroom in the fourth seat • From x = 2 m to x = -5 m • From x1 = 2 m to x2 = 5 m • At x = -4.5 cm • 3 miles to drive to Salem • Δx = 24.5 m