Straight Motion

• Motion


  Change in position of a body with respect to time
• Rest


  When a body's velocity is zero with respect to time
• When a body's velocity is zero


  It is said to be at rest
• When a body's velocity is not zero

  It is said to be in motion
• Rest and motion are relative terms
• Absolute rest


  • To know whether position of an object changes with time, a point absolutely fixed in space has to be chosen as reference
• An object may be at rest with respect to one object and at the same time it may be in motion relative to another object
• in unverse
• object is in
• is known
• Distance


  Length of actual path covered by a body during its initial and final positions.
• Displacement


  Change in position of an object in fixed direction<|>Shortest (Straight line) path measured in the direction from initial to final positions<|>SI unit: m<|>CGS unit: cm<|>It is vector (has both direction & magnitude)<|>Can be +ve, -ve or zero
• Displacement Characteristics


  • Has the units of lengths
  • Can be +ve, -ve & zero
  • Not dependent on choice of origin of position coordination
  • The actual distance travelled is greater than displacement
  • Unique path b/w two points from initial & final
  • Does not give any info of pathway that is actually travelled
• Speed


  Rate of change of position of an object with time in any direction<|>It is scalar quantity<|>Speed = Distance Travelled / Time Taken<|>Can be +ve or zero
• Types of Speed


  • Uniform speed
  • Variable speed
  • Average speed
  • Instantaneous speed
• Velocity


  Rate of change of position of an object with time in a given direction<|>It is vector quantity<|>Velocity = Displacement / Time<|>Can be +ve, zero or -ve
• Types of Velocity


  • Uniform velocity
  • Variable Velocity
  • Average velocity
  • Instantaneous velocity
• Straight Line Motion Graph-

  Displacement - Time Graph [(x -t) graph]<|>Velocity = Slope of (x -t) graph<|>Acceleration = Slope of (v -t) graph
• When acceleration takes its direction as negative it is taking U-teren after getting [V=0]
• object cannot be present at 2 points in the given same time. Therefore, this graph is impossible