Announcements

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Announcements

• Homework for tomorrow
• (Ch. 3, Problem 23 )
• Office hours
• M 1-2 pm
• T 1130-1230 pm
• WF 3-4 pm
• R 10-11 am
• Tutorial Learning Center - Houston Hall 110
• MWF 8am-5pm
• T 8-10am, 11am-2pm, 3-5pm
• R 8-9am, 11am-5pm

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Chapter 3

• Vectors Motion in 2D
• (Motion in 2D)

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Section 3.3 Displacement, Velocity, and
Acceleration in 2D

• The displacement of an object is defined as the
  change in its position

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Velocity

• Average velocity is the ratio of the displacement
  to the time interval for that displacement
• The instantaneous velocity is the limit of the
  average velocity as ?t approaches zero
• Velocity is tangent to the path, pointing in the
  direction of motion

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Acceleration

• Average Acceleration is the ratio of the change
  in velocity divided by the time interval for that
  change in velocity
• The instantaneous acceleration is the limit of
  the average acceleration as ?t approaches zero
• is in the direction of not

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Ways an Object Might Accelerate

• The magnitude of the velocity can change
• The direction of the velocity can change
• Even though the magnitude is constant
• Both can change

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Quiz Question 1

• Consider the following controls in an automobile
  gas pedal, brake, steering wheel. The controls
  in this list that cause an acceleration of the
  car are
• all three controls
• the gas pedal and the brake
• only the brake
• only the gas pedal.

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Quiz Question 2

• Which of the following objects cant be
  accelerating?
• an object moving with a constant speed
• an object moving with a constant velocity
• an object moving along a curve.

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Section 3.4Motion in 2D

• Projectile Motion
• The object moves in both the x and y directions
  simultaneously
• Object will follow the path of a parabola!

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Projectile Motion continued

• The x- and y-directions of motion are completely
  independent of each other!
• Motion in the x-direction is uniform motion
• Motion in the y-direction is free fall

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Projectile Motion continued

• Simply apply our kinematic equations to each
  component of motion

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Projectile Motion continued..

• The Kinematic Equations become

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Serway Prob 22

• One of the fastest recorded pitches in
  major-league baseball, thrown by Joel Zumaya in
  2006, was clocked at 101.0 mi/h.
• If a pitch were thrown horizontally with this
  velocity, how far would the ball fall vertically
  by the time it reached home plate, 60.5 ft away?