chapter 2

• 5 common scalar quantities


  distance, speed, mass, energy, time
• 5 common vector quantities

  displacement, acceleration, weight, force, velocity
• how to find speed?

  distance divided by time taken
• how to find velocity?

  displacement divided by time taken
• vector diagram

  choose an appropriate scale to represent the vectors
• how to find average speed?

  total distance travelled divided by total time taken
• constant or uniform speed


  change in distance travelled by an object for every unit of time is the same
• displacement

  distance measured in a straight line from a fixed reference point
• velocity


  rate of change in displacement
• how to find acceleration?

  velocity divided by time taken
• constant or uniform acceleration

  change in velocity of an object per unit time is the same
• how to find acceleration?

  (final velocity minus initial velocity) divided by change in temperature
• non uniform acceleration

  change in velocity per unit time is not the same
• displacement time graph

  gradient of the graph is the velocity of the object

  • when gradient is zero, velocity is zero, object is at rest
  • when gradient is constant, uniform velocity
  • when gradient is increasing, velocity is increasing, non uniform velocity
  • when gradient is decreasing, velocity is decreasing, non uniform velocity
• velocity time graph

  gradient of the graph is the acceleration of the object

  • when velocity and gradient is zero, acceleration is zero, car at rest
  • when only gradient is zero, car is moving but acceleration is zero
  • when gradient is positive and constant, acceleration is constant
  • when gradient is negative and constant, deceleration is constant
  • when gradient is positive and increasing, acceleration is increasing
  • when gradient is positive and decreasing, acceleration is decreasing
• 10m/s^2

  acceleration of free fall for a body near to Earth is constant

  acceleration due to gravity for objects on Earth is constant