2.6 Motion with Constant Acceleration
Reaction Time
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Instructions:
Click on the start button to start the simulation. The
simulation mimics a traffic light situation. The idea is to press the brake button
whenever the traffic light turns red. The applet measures your reaction time (delay
between the instant the traffic light turns red and the instant you press the brake
button,) the time it takes the car to stop and all related distances. The total
distance traveled by the car after the light turns red, as well as the distance traveled
while braking and the distance traveled before braking are shown on the applet canvas
after the car stops. The reaction time (Delay) and the time during braking (Brake)
are shown in a box below the canvas.
You can change the initial speed of the car by simply typing the number at the box labeled
"V =" and by selecting the unit from the drop down menu. You can also set
the coefficient of friction between the tires of the car and the road by typing the
number. The applet canvas displays a velocity scale in red at the right and a position
scale in black at the top. The graph displayed is a velocity versus position graph.
You may use the "Mouse X,V" box to get graph coordinates. Navigation: Once you invoke the applet, you can return to this
window by using the standard close box of the applet window (top right corner box in
Windows platforms and top left corner on Mac platforms.) |
Your browser can't run 1.0 Java applets, so here's a picture of the window the program
brings up:
Explanation:
Before you press the "Brake" button, the car moves at
constant velocity. You can find the distance traveled during this delay period by
using equation 2.3. Once the "Brake" button is pressed, the motion is at
constant acceleration. Note that the initial velocity and final velocity are known.
The time is calculated by the applet. You can use the equations in Table 2.1
to determine the acceleration and distance traveled by the car during this time interval.
You may want to revisit this applet when you get to section 4.8. You can then
find the acceleration by determining the friction force and using Newton's second law of
motion.
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Source:
Fu-Kwun HwangGo to the web site and link to the Online Library for further information.
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