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Information about this web site => Request for physics Simulations => Topic started by: Kennyg10 on August 05, 2009, 11:49:47 pm

Title: 4 car collision going through two intersections
Post by: Kennyg10 on August 05, 2009, 11:49:47 pm
You are at a crossing intersection of a bypass of a major highway. You have to go through 1 light and then another light. There are 4 vehicles in the second to left turning lane. The light just turns green and the 4 vehicles start to move forward. In the perpendicular incoming traffic a police police motor cycle darts out into the intersection to escort a truck through. Causing the 1st car to come to a halt, the second car to come to a halt of 1ft from it and the 3rd car to actually slam into the back of it, and the 4Th vehicle to slightly hit the 3rd car. The 4Th car was going 5 to 6 mph and increasing. The 3rd car was already going at a speed of 9 to 12 mph, the 2ND was slowing down to about 5 mph, and the 1st car was stopped already. Is it possible to create a simulation that shows the initial collision of the wreck that started from the Police motorcycle crossing into the intersection and causing 4 vehicles who have a green light to go and had the intentions of progressing through the light without stopping... Basically could you create a simulation of a typical flow of four vehicles through an intersection, showing the rate of impact if they all were traveling at a nominal speed of 5 to 10 mph and how much of an impact would each occur if had to come to a halt. Starting from the 1st to the 4Th vehicle.

Title: Re: 4 car collision going through two intersections
Post by: Fu-Kwun Hwang on August 06, 2009, 11:51:32 am
To simulate motion of an object with constant speed or constant acceleration, two initial conditions are needed: i.e. position and velocity.
There are four vehicles, so distance between vehicles and velocitry of each vehicles are important parameters.
The reaction time (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=137.0) for each driver also affect the timing the brake beening hit, along with the above information can be used to determined when the car are fully stopped or when the car collide with another one.
If the frition coefficient is $\mu$, the acceleration $a=-g \mu$, and $V(t)=V(t=0)+a t=V(t=0)- g \mu t$.

The impact force can be calculated if the time interval between collision happened and the car fully stopped is available. $F=\tfrac{\Delta P}{\Delta t}$.

Please check out Reaction time and car accident (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=138.0) (may be you can find out the information you need.). 
Ejs version of traffic control simulation (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=365.0)