Vectors and Scalars

• Vector quantities have magnitude and direction
• Scalar quantities have magnitude only
• Examples of vector quantities are: Force, Velocity, Displacement, Acceleration and Weight
• Examples of scalar quantities are speed, distance, mass, time, energy and power
• To calculate the resultant of two vectors in one dimension:

  • add them if acting in same direction
  • subtract them if acting in opposite direction
• To calculate the resultant of two vectors at right angles:

  • make sure they are head to tail
  • use Pythagoras to get size
  • use SOHCAHTOA to get direction
• The area under a speed-time graph equals distance
• The area under a velocity-time graph equals displacement