physics - motion

• What is distance?

  Distance is how far an object moves and does not involve direction. It is a scalar quantity.
• What is displacement?

  Displacement includes both the distance an object moves, measured in a straight line from the start point to the finish point and the direction of that straight line. It is a vector quantity and should be expressed in terms of magnitude and direction.
• Does speed involve direction?

  No, it is a scalar quantity.
• What is velocity?

  The velocity of an object is its speed in a given direction. Velocity is a vector quantity.
• What is a scalar quantity?

  Scalars are quantities that have magnitude only.
• What is a vector quantity?

  Vectors are quantities that have magnitude and an associated direction.
• What are examples of scalars?


  Distance, speed and time
• What are examples of vectors?

  Displacement, velocity, acceleration, force and momentum
• What are examples of objects which have a constant speed but at the same time, a changing velocity?

  When an object moves in a circle the direction is continually changing. This means that an object moving in a circle at constant speed has a continually changing velocity.
• velocity = distance / time (v=s/t)
• What are some factors which can affect the speed of a person?

  Age, terrain, fitness and distance travelled
• What are the typical values for walking?

  1.5 m/s
• What are the typical values for running?

  3 m/s
• What are the typical values for cycling?

  6 m/s
• What type of graph can represent how far an object has travelled?


  If an object moves along a straight line, how far it has travelled can be represented by a distance–time graph.
• How can the speed of an object be determined using a graph?


  The gradient of the line
• How can speed be determined at any particular time if an object is accelerating?

  If an object is accelerating, its speed at any particular time can be determined by drawing a tangent and measuring the gradient of the distance–time graph at that time.
• Acceleration = Change in velocity / Time taken
• An object that slows down (decelerates) has a negative acceleration.
• The acceleration of an object can be calculated from the gradient of a velocity–time graph
• The distance travelled can be calculated from the area under a velocity–time graph.
• Distance travelled = Speed x Time