NTNU JAVA

Posted: Thu Jan 29, 2004 1:33 am Post subject: Reaction time measurement

Reaction time : the lapse of time between stimulation and the beginning of response.

You are driving on the high way and listening to the music you like most.

Suddently, you see the brake light of the car in front of you just turned on.

You will try to hit the brake and slow down your car.

But, there is a small time delay before you really do that--- your reaction time.

During that period of time, your car is still moving at the same HIGH speed!

If you do not want something VERY BAD happened,

What is minimum diatance between front of your car and the rear of the car before yours?

If both cars need the same distance to fully stopped, the miniuum distance = ( the velocity of your car )* ( your reaction time )

Would you like to measure your reation time?
Would you like to estimate how fast you can drive safely on the highway?

Click Start to start the animation. Click Brake to stop the car.

The time delay between the red light is turned on and you click the brake button will be shown in the textfield.
(plus the time needed to stop the car after the brake is started. The corresponds distances which the car moved are also shown on the graph)

Paramenters you can change

Initial Velocity of the car : initial value is 72 km/h = 20 m/s
You can select the unit for the velocity ( km/h, mile/h or m/s)

Friction coefficient of tires on the road : initial value is 0.8

Typical value of tires	static coefficient	kinetic coefficient
auto tires on dry concrete	1.0	0.7-0.8
auto tires on wet concrete	0.7	0.5
auto tires on icyconcrete	0.3	0.02

The Y-coordinate the the small dots are proportional to the velocity of the car
Notice that it is not a straight line after the brake turned on! Because ...

The mouseXV textfield shows X-coordinate and velocity of the car at the mouse position.
If you drag the mouse, it will change to values of the relative distance and the relative velocity.
(relative to the point where you started to drag the mouse)

Press Reset button to restart the testing.

Close the window to Quit.

Posted: Mon Feb 09, 2004 11:41 pm Post subject:

Dr. Hwang,

I appreciate your reaction time testing device. Is there any data about how the normal population reacts with your device? To measure reaction time, in seconds, do you divide by 20? Is the 20 meters per second?

Thanks for your help.

Steve sbw@dscience.com

Posted: Mon Feb 09, 2004 11:42 pm Post subject:

The first textfield (under label V=) is the velocity of the car. It is not the reaction time.
The reaction time is shown in the textfield under the label : Delay +Brake
where "Delay" is the reaction time and "Brake" is the time for the car to fully stopped.

Posted: Mon May 17, 2004 9:29 am Post subject: Reaction time applet

Dr Hwang

Enjoy your site and use it all the time with my Physics classes.

I think your calculation of braking distance is wrong on the Reaction Time Measurement applet.

It always displays as 25.5 m regardless of speed.

It should increase as the square of speed. Can you fix this?

Paul

Posted: Mon May 24, 2004 6:05 am Post subject:

I think you forgot to hit ENTER after you have changed the number in the textFields.

Please try it again and it should work fine.

Posted: Wed Aug 04, 2004 12:01 am Post subject: Re: Reaction time measurement

Posted: Wed Aug 04, 2004 12:04 am Post subject: Re: Reaction time measurement

Hi Hawg, I think this is the coolest site and I shall tell all my friends about this site!