Unit I-1: Kinematics in 1D and 2D

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Unit I-1 Kinematics in 1D and 2D

• Part 1- Speed and Velocity

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ANNOUNCEMENTS

• Lab donation?
• Selfie?
• 2L bottles?
• Check www.hondorfphysics.weebly.com frequently
  for assignments, downloads, power points and labs

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Location, location, location!

• To define location you need 3 pieces of
  information
• Distance
• Direction
• Reference point

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Distance How far between two points
Displacement How far between two points in a
certain direction.
Scalar Quantity A quantity with magnitude
(size) only.
Examples distance, mass, volume
Vector Quantity A quantity with magnitude AND
direction.
Examples displacement, force, velocity
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Location is important, but moving is more fun!
Unless youre an electron, or God, this will
take some time.
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Changing your location

• Rate of change of distance speed
• s
• Units-

• Rate of change of displacement velocity
• v
• Units-

d t
d t
m s
m s
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There are 3 types of velocity

• Constant
• Average
• Instantaneous

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Constant Velocity

• Same speed
• Same direction
• NOT REALISTIC!

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Average Velocity

• Usually over a long distance
• Example
• Trip to the In-laws, St. Augustine, FL
• Roughly 400 miles, south
• Takes about 8 hours- lots of pit stops!
• vavg dtotal or 50 mph
• ttotal
• Most of the time were really going closer to 80
  mph
• Sometimes, we are going 0 mph!

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Instantaneous Velocity

• Velocity at an instant in time
• How long is an instant?
• Try v d/t with a distance of your choice and t
  0
• Can you measure instantaneous velocity?
• Can you calculate instantaneous velocity?
• Actually..you can! Use CALCULUS!

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d vs. t graph
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ONE LAST WARNING

• ALWAYS!
• ALWAYS!
• ALWAYS!
• USE UNITS!!!!