D-1

=P-2=

Rob, Will, Tony

GROUP CONTRACT:

=Reformatted Powerpoint=
 * this was posted only the night before the trial but it contains no additional information that was not previously disclosed on the previous powerpoint linked further down the page labeled "car crash"**



=Daily Group Log:=

4/23: Today we spent the period looking up information about both cars and are in the process of figuring out our calculations. Will and Tony will split the calculations and figure out how fast both cars were going before the crash. Robbie will go to the crash site and take pictures of the surrounding area to paste on a poster board to use as a visual aid. Accident Scene Pictures





Car Data: MV1: 2002 Subaru Forester

MV2:

Picture Exhibits





4/26: As a group we worked on the calculations. Once we finish the crush lab, we can use this data to figure out how fast the cars were going before they applied the breaks. The most recent version of the document with this information is posted below. (Last Updated: May 3, 2010)

Exhibit C**:**

4/27: Today our group worked on the crush lab. We dropped the ball on the can and measured the distances of the indentations that the ball made into the can. These measurements were put into an excel document to try and figure out the velocity with which the ball hit the can.



4/28: Robbie and Will finished the calculations relating the crush data from the accident to find out how fast the cars were traveling at impact. This information shows how fast the cars were traveling after breaking (i.e. these speeds should be slower than their initial velocities).





Objective**: To figure out how fast the cars were going after they initially braked.**



Calculations:

Conclusion**: The EDR in MV2 (Ford Focus) recorded that the car was traveling at a speed of 23.4 mph (10.461 m/s) at the time of the crash. This velocity as well as the CE values given by Bilash Burns LLC were used to calculate the speed of both cars after they hit. Using the equation KEinitial + Work = KEfinal we were able to find the initial and final velocities of both cars. The final velocity for MV2 was found first by rearranging the aformentioned equation. This speed was then applied as the final velocity for MV1 after the crash because both cars have the same final velocity because they were attached. This was then used to find the speed of MV1 (Subaru Forester) after breaking. This speed, 24.048 mph can be used to figure out how fast the car was going before it applied the breaks and crashed into MV2 (Ford Focus). These calculations are found in the document labeled "Car Crush Calculations" above.**

Force on the Driver



W = weight (assumed 170 average weight of 40year old male) V (at impact) =feet/sec (22.2 mph) D = .2 (distance of impact)

The Force Required to break a bone is 4.1 kg or 9.0389528 lbs of force to break a bone We inquired that he received over 1,570.22 x the required about of lbs of force to break a bone applied to the side of the driver, which would break his arm, leg and his entire left side of his body, this would kill the man. If the man was driving slower and had more time to slow down, then

4/29: Will and Robbie completed the reaction time lab as well as the lab to find the coefficient of friction. The reaction time lab and the coefficient of friction are both going to be used in the trial as well as to calculate the speeds of the cars more correctly.





Conclusion**: In this experiment we put weights of varying amounts onto a board with a piece of rubber tire on the bottom to figure out the coefficient of friction between the tire and the asphalt. The site where we conducted the experiment was on a flat dry asphalt surface during the day in sunny weather. According to the accident report the crash occurred at 7 am in sunny weather so no other factors could have affected the coefficient of friction we found. By using a force meter to pull the drag sled across the pavement we calculated the tension force. Since we knew the weights we were able to find the Normal Force of the drag sled and thus plot the data points on a graph to figure out the coefficient of friction.



5/3/10: Will worked on figuring out the effect that the reaction time would have had on the breaking distance of MV1 since Mill Road is a blind spot. The data for the lab Robbie and Will completed is below. Will created a diagram of the crash scene with information about the reaction times posted above. The file name is "Retelling of the crash.ppt"

5/4/10: Robbie fixed the calculations for the crush velocities and posted them above. He redid the derivations of the formulas and found reasonable values for the initial and final velocities of both cars after breaking and after the crash respectively. He also used this new found information to redo the initial velocities of the cars before breaking. Tony worked on the powerpoint adding more pictures and diagrams of the cars travelling toward the intersection (the most recent version will be posted tonight). Will worked on his opening speech and questions for tomorrow (or thursday's trial) and helped Tony with the powerpoint.