This is what a velocity-time graph represents. It helps you calculate reaction time and the time it takes for a vehicle to stop.
Look at the graph and answer the questions.
What is the driver’s reaction time?
What was the speed of the vehicle before it started to brake?
What distance was travelled while the driver was reacting (the thinking distance)?
The area under the flat part of the graph, which is 15 m/s × 0.8 s = 12 m.
How long did it take the car to stop?
The time between 0.8 s and 4 s = 3.2 s.
What is the braking distance?
The area of the triangle.
½ × base × height = ½ × 3.2 s × 15 m/s = 24 m
What is the total stopping distance?
12 m + 24 m = 36 m