Chapter 2 Kinematics

• Mechanics


  The study of motion
• Celestial objects and our Earth are always moving
• Even objects that appear to be still have atoms and molecules that vibrate in continuous motion
• Kinematics


  The study of motion without considering its causes
• Rest


  An object does not change its position with respect to an observer
• Motion


  An object is changing its position
• Types of motion


  • Translatory motion
  • Rotatory motion
  • Vibratory motion
• Translatory motion


  • All points of a moving object move uniformly in the same direction, with no change in the object's orientation
• Kinematics


  Branch of Mechanics in which we study about motion of objects without reference to their cause
• Two observers can have different opinion about rest and motion of an object
• Types of Translatory Motion

  • Rectilinear Motion
  • Circular/Curvilinear Motion
  • Random Motion
• Rectilinear Motion

  • Body moves from one point to another in a straight line, eg. bus
• Circular/Curvilinear Motion


  • When a body moves in a circle, eg. roller coaster, Earth around Sun
• Random Motion


  • Irregular path, eg. kite
• Rotatory Motion


  When a body moves in a circular path (about its axis/on a fixed point)
• Vibratory Motion


  Body moves to back and forth about its main position
• Distance


  Actual length between two points
• Displacement


  Shortest directed distance from one point to another
• Displacement can never be greater than Distance
• Distance and displacement are equal when an object is moving on a straight path
• Displacement is represented by the symbol d→
• Speed


  • Symbol "v"
  • Formula: Distance / time
  • Unit: m/s
  • Scalar quantity
• Speed


  • Direct (x∝y)
  • Inverse (x∝1/y)
• Types of Speed


  • Instantaneous Speed
  • Average Speed
• Instantaneous Speed


  Speed of object at any specific instant
• Average Speed


  Total Distance / total time
• Uniform Speed


  Body covers equal distance in equal time
• Variable Speed


  Body does not cover equal distance in equal time
• Speedometer is used to measure object speed at any instant
• Velocity


  • Displacement covered in a unit time
  • Symbol "v"
  • Unit: m/s
  • Vector Quantity
• Types of Velocity


  • Average Velocity
  • Instantaneous Velocity
  • Uniform Velocity
• Average Velocity


  Total displacement / Total time
• Instantaneous Velocity


  Velocity of object at any specific instant for small interval of time
• Uniform Velocity


  Body covers equal displacement in equal time
• Variable Velocity


  The velocity that changes
• Velocity


  Speed + Direction
• Acceleration


  Velocity + Direction
• Acceleration


  Change in velocity per unit time
• Formula for Acceleration


  A = (V₂ - V₁) / (t₂ - t₁)
• Acceleration is a vector quantity