distance, speed and acceleration

• these terms describe the motion of a body:

  • stationary
  • constant speed or velocity
  • accelerating
  • decelerating
• velocity:

  the speed in a specific direction.
• motion is described using distance-time graphs and velocity-time graphs. it is important to work out which type it is before you start to describe the graph as the shapes represent different things on each type. labelling on the axes can help you recognise which graph is which.
• these are the types of graphs:

  
• calculating speed (or velocity):

  speed (m/s)= distance (m)/time (s)
• calculating acceleration (or deceleration):

  acceleration (m/s$^2$)= change in velocity (m/s)/time (s)
• using velocity time graphs:

  the acceleration or deceleration can be calculated by calculating the gradient of the line. where as the distance travelled can be calculated by calculating the area under the line of the graph.

  
• total stopping distance = thinking distance + braking distance