Chapter 2

• Motion


  The position of an object should change
• Types of motion


  • Rectilinear motion (linear motion, motion in a straight line)
  • Motion in a plane (2D motion)
  • Motion in 3D
• You cannot determine if an object is in motion or at rest just by looking at it
• Reference point


  A point assumed to be at rest and used to define the position of an object
• Frame of reference


  The coordinate system used to describe the position and motion of an object
• The Earth is not moving with respect to an observer residing on Earth, but is moving with respect to an observer in outer space
• If two people X and Y are sitting in the same fast moving car

  They will observe the same motion relative to each other
• Distance


  The total path length traveled
• Displacement


  The shortest distance between the initial and final positions
• Distance is always greater than or equal to displacement
• Scalar


  A quantity with only magnitude, no direction
• Vector


  A quantity with both magnitude and direction
• Distance is a scalar, displacement is a vector
• Displacement does not depend on the path taken, only on the initial and final positions
• Distance


  A scale, only has magnitude, does not care about direction