OH SHOOT Y'ALL, YELLOW LIGHT!!!
You know the moment when you're driving down the road and suddenly the light changes from green to yellow?! You take that extra second to think about whether to slow down or continue through the light, before flooring it and running the red light anyway.
If you're an ambulance, yellow lights do not apply.
Wanting to take a more physics-ical approach to this issue, we stood on the corner of Balcones and 2222 gathering data (and eating fro-yo: thanks Berry Austin!). We timed the length of the yellow light and the length of the intersection (using state of the art measuring equipment, see video below) and used this to calculate how long it would take to get through the light safely.
DATA:
Length of the intersection: 58.25 feet
Length of yellow light: 3.8 seconds
Speed Limit (feet/sec): 51.3 ft/s
Using the equation: v=d/t we are able to determine the maximum distance away from the intersection that a car can be and still make it (safely) through the light.
*And by safely we mean that all parts of the car must clear the intersection by the time the light turns red.
Maximum distance away from the intersection when the light turns yellow: 136.72 ft
Time it takes to get through the intersection going the speed limit: 1.135 seconds
Time left over: 2.665 seconds
According to James Madison University, the average stopping distance of a car traveling 35 mph will take 135 feet to come to a complete stop, confirming that the yellow light at this intersection will give a driver enough time and room to stop (taking into account human reaction time) before the light turns red at the maximum distance. Note: when we set up this distance on Sunshine, Abby's car (RIP) was able to stop in about 2/3 of that.
BUT WAIT, THERE'S MORE!
What if you want to speed up to make it through the light? We came up with a function of position vs acceleration to determine if you're an "x" distance away, how much you have to acclerate to get through the light safely. Exciting!!!
Δx=v0(t)=.5at²
plug in the data and you get...
a=x/4.5
*Our data isn't perfect, but it's pretty damn close. We don't know how to calculate percent error but we know we're sorta wrong.
Bibliography:
"Signals, Signs, and Markers." Texas Drivers Handbook. Austin: DPS, 2008. Http://www.txdps.state.tx.us/DriverLicense/documents/DL-7.pdf. Texas DPS. Web. 25 Oct. 2011. <www.txdps.state.tx.us
"What to Do When the Light Turns Yellow?" Driver's Ed Guru. Web. 25 Oct. 2011. <http://www.driversedguru.com/driving-articles/drivers-ed-extras/what-to-do-when-the-light-turns-yellow/>.
"Ratio of Speed to Stopping Distance." James Madison University - Home. Web. 25 Oct. 2011. <http://www.jmu.edu/safetyplan/vehicle/generaldriver/stoppingdistance.shtml>.
Brought to you by contributions from viewers like you, Lonnie:
Straight pimpin' on the corner
