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Software Requirements


Android iOS Windows MacOS
with best with Chrome Chrome Chrome Chrome
support full-screen? Yes. Chrome/Opera No. Firefox/ Samsung Internet Not yet Yes Yes
cannot work on some mobile browser that don't understand JavaScript such as.....
cannot work on Internet Explorer 9 and below



Fu Kwun Hwang; Fremont Teng; Lawrence Wee

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Sample Learning Goals

Reaction time (RT) is the elapsed time between the presentation of a sensory stimulus and the subsequent behavioral response. Imagine that you are driving on the high way, and suddenly, you see the brake light of the car in front of you just turned on. You will of course try to hit the brakes  to slow down your car. But, there is a small time delay before you really do that and that is your reaction time. During that period of your reaction time, your car is still moving at the same HIGH speed! 
So, what is the minimum distance between the front of your car and the rear of the car before yours?  Assume that both cars need the same distance to fully stopped, the minimum distance is the velocity of your car multiply by your reaction time.                            

This javascript applet helps you to determine your own reaction time and therefore based on the formula, calculate the distance to keep between cars when you are on the highway.

Click on the Play button to start the red car which will move with an initial velocity selectable from the slider bar.
The traffic light will turn from green to yellow, then to red at a randomly generated time interval.
Click on the brake button when you see the red light turned on.

The green, yellow and red arrows indicate the car's position when the green, yellow and red light started turned on.

The black and blue arrows indicate the car's position when you hit the brake and the position when the car is fully stopped.
The distance between the RED and BLACK arrows is the minimum distance to keep.
Your reaction time, brake time/distance are all shown in the text field.
Drive safely!

For Teachers

Traffic Light Reaction Time Simulator Javascript Simulation Applet HTML5



Tabbed Panel and Options

Toggling the tabbed panel will give you their respective options
(Toggling Display)


(Toggling Initial Velocity)


(Toggling Friction Coefficient)

Running the Simulation using Buttons

(Start of the Simulation)
Click Play to start the simulation
The car will start to move
(Light changes Yellow)
The light then changes to yellow.
It is an indicator for the user to get ready to press the stop (square) button beside the play button.
(Light changes Red)
When the traffic light turns red, the stop button will be enable.
Click on it!
(Car stops)
Watch as the car halts all movements.
Read your reaction time from the graph below.

Toggling Full Screen

Double tap anywhere on the screen to toggle full screen.

Reset Button

Resets the simulation.






  1. Javascript version by Hwang Fu-Kwun, lookang and Fremont
  2. Java version by Hwang Fu-Kwun and lookang
  3. Java version by Hwang Fu-Kwun

Other Resources


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