Topic 2- motions and forces

• These quantities have only magnitude

  Scalar
• These quantities have magnitude and direction

  Vector
• VF.WAMD- these are vectors, name the 6 vectors that these letters stand for

  Velocity, Force, Weight, Acceleration, Momentum, Displacement
• Speed =


  Distance/Time
• Distance=


  Speed x Time
• Time=


  Distance/Speed
• The typical speed of a walker (m/s)

  1
• The typical speed of a sprinter (m/s)

  10
• The typical speed of a car on the motorway (m/s)

  30
• The typical speed of a cyclist (m/s)

  15
• The typical speed of a gale wind (m/s)

  20
• The speed of sound in air (m/s)

  330
• The speed of light in a vacuum (m/s)

  300, 000, 000
• A light gate measures time (not speed). It must be used with an interrupt card of known length, and a computer for the results to be calculated as speed.
• Acceleration=


  Change in velocity/Time
• Acceleration is the gradient of a velocity vs. time graph.
• Distance travelled is the area under a velocity vs. time graph.
• Newton's First Law


  Objects remain at rest, or move at a constant velocity, unless acted on by an external force.
• Newton's Second Law


  Unbalanced forces will result in acceleration. Force= Mass x Acceleration.
• Newton's Third Law


  Every action has an equal and opposite reaction.
• Force=


  Change in momentum/Time
• Mass of the vehicle, State of the vehicle's brakes, Speed of the vehicle, Friction between the tyres and the road, State of the road, Driver's reaction time- are all examples of what?

  Factors affecting the stopping distance of a vehicle.