You are driving down a straight highway at 20 m/s (72 km/h) on a foggy night. Suddenly you see a truck stopped directly in front of you a distance d down the roadway.

Hints on drawing the graph

  • Use quad ruled paper (either 1/4 inch or 5 mm per square) and sketch a graph to scale. How to choose a scale
  • During the first second (the reaction time), the velocity is constant. That would be a horizontal line.
  • After the first second, the constant deceleration of 4 m/s2 is a straight line with slope -4 on the graph of velocity in m/s vs time in s.
    • Deceleration : slowing down.
      In physics the word "acceleration" includes the meaning deceleration where the direction of the acceleration is opposite to the direction of the velocity.

What to do

Draw the graph.
After you have drawn your graph compare it to our graph and continue.
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