chapter 1 (scalar/vector)

• Scalar quantities


  Physical quantities with magnitude only
• Vector quantities


  Physical quantities with both magnitude and direction
• Examples of scalar quantities


  • Distance
  • Time
  • Current
  • Temperature
  • Electric current
  • Volume
  • Speed
  • Mass
  • Energy
• Examples of vector quantities

  • Force
  • Weight
  • Velocity
  • Acceleration
  • Momentum
  • Electric field strength
  • Gravitational field strength
• When forces have the same magnitude but different directions


  They will cause different resultant motions
• Expressing vector quantities


  Magnitude and direction (e.g. 10 Newton right, +10 Newton)
• Calculating resultant force


  1. Add forces in same direction

  2. Subtract forces in opposite directions
• Scalar vs vector quantities


  • Distance vs displacement
  • Speed vs velocity
• Speed and velocity have the same SI unit of meters per second
• Two cars moving in opposite directions

  Have the same speed but different velocities (e.g. +60 km/h vs -60 km/h)
• Magnitude


  A measure of the size or extent of something
• Direction


  The course along which something moves
• Speed


  How fast an object is moving, measured in the SI unit of meters per second
• Velocity


  How fast an object is moving, also measured in the SI unit of meters per second, but takes into account the direction in which the object is moving
• Speed and velocity


  They are not the same thing, velocity has to take into account the direction in which the object is moving
• Calculating speed


  Distance divided by time
• Calculating velocity


  Displacement divided by time
• Comparison of speed and velocity

  • Two cars moving in opposite directions at 60 km/hour have the same speed but different velocities (positive 60 km/hour and negative 60 km/hour)
• Scalar quantity


  A quantity that has magnitude but no direction, like distance and speed
• Vector quantity


  A quantity that has both magnitude and direction, like displacement and velocity
• Distance vs Displacement


  • Distance is the total distance traveled, displacement is the net change in position from start to end (can be positive or negative)
• Calculating displacement


  Find the start and end points, and the direction between them
• When calculating distance, direction doesn't matter, but when calculating displacement, direction is important
• Calculating speed and velocity

  • Speed = distance/time, velocity = displacement/time
• If an object starts and ends at the same point, the displacement is zero, even if it moved around
• Calculating distance, displacement, speed and velocity for a more complex path

  • Distance = 7 km, displacement = 5 km at 53.1 degrees, speed = 7 km/h, velocity = 5 km/h at 53.1 degrees