(Physics) distance and speed

• Distance


  How far it's traveled
• Time

  Time from start / between time intervals
• Speed


  How fast an object is moving
• Velocity


  How fast/slow an object moves, given direction
• Acceleration


  Rate of object speeding up or slowing down
• Speed is a scalar quantity (only has magnitude)
• Velocity is a vector quantity (has magnitude and direction)
• Distance-Time Graph


  1. Allows us to measure the speed of the object

  2. Gradient shows speed
• A moving object with constant velocity has a straight line on a Distance-Time Graph
• The gradient of a Distance-Time Graph is the acceleration of the object
• Velocity-Time Graph


  Accelerating at a constant rate
• Thinking distance


  Distance travelled when driver sees hazard, thinking to brake
• Braking distance


  Distance it takes for the vehicle to decelerate to a stop once brakes are applied
• What affects thinking distance?


  • Reaction time of driver (alcohol, drugs)
  • Distracted (phone)
  • Velocity
• What affects braking distance?


  • Velocity of car
  • Mass of car
  • Condition of tyres
  • Wet/icy conditions
• Safety features: seat belts, air bags, crumple zones, reduce speed