Motion

1
Chapter 3

• Motion

2
Objectives

• Speed vs. velocity
• Use vectors in velocity problems
• Velocity vs. acceleration
• Use vectors to solve acceleration problems
• Motion of object in free fall
• Solve 2-D motion problems
• Calculate range of projectile motion

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3.1 Speed Versus Velocity

• Mechanics study of motion
• Motion an object's change in position
• Speed how quickly an object changes position

4

• Determining very important in science
  technology
• Ex motion of vehicle
• Speed distance traveled per unit of time
• speed distance/time s d/t
• (mi/h, km/h, m/s, ft/s)
• Scalar quantity (no direction)

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Velocity

• Velocity is rate of motion in a particular
  direction
• Velocity is a vector that represents speed and
  direction
• vavg s/t or s vavgt
• where vavg average velocity t time
• and s displacement or distance

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3.2 Acceleration

• Acceleration is the change in velocity per unit
  time
• aavg change in velocity/elapsed time
• (final velocity initial velocity) /
  time
• a (vf vi)/t -or- ?v/t - or- ?v
  at
• aavg average acceleration t time
• ?v change in velocity

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Acceleration vs. Deceleration

• Deceleration means object is slowing down
• If acceleration is positive speeding up
• If acceleration is negative slowing down
  (deceleration)
• Final velocity will be less than initial
• If object comes to a stop, final velocity 0
• If object starts from rest, initial velocity 0