7P1

= Evidence Crash Case #1 = Today, Liana and Marlene made our contract. Andrew and Eric were on a field trip, therefore we did not decide on a group leader yet.
 * April 16, 2010**

Andrew: Was absent the previous week from Wednesday-Friday and returned home on Sunday (Robotics Competition in Atlanta). Note: Had no Internet. Received an email from Liana regarding the group contract. Read and signed it. Downloaded and reviewed the group crash scenario assigned.
 * April 19, 2010**

Andrew: Expert Witnesses came in to talk; worked on a problem using skid marks. Liana: Learned about car crash scenarios and skid marks from Expert Witnesses. Marlene: Watched in class assembly with Expert Witnesses on Car Crash Scenarios.
 * April 20, 2010**

Andrew: Worked on and completed the Edheads activity at home. Liana: Edheads activity Marlene: Read ELVA (Technical Assisant Section) Eric: Started Edheads activity. Listened and gathered information provided through activity.
 * April 21, 2010**

Andrew: Read the ELVA book (expert witness). Liana: ELVA book (prosecuter) Marlene: Started Edhead's Activity. Eric: Read ELVA book (policeman)
 * April 22, 2010**

Andrew: Completed reflection sheet on what I did so far (Edheads, Presentation by Experts, ELVA). Liana: reflection sheet about the project so far Marlene: Finished Edhead's Activity and completed Reflection on project. Eric: Worked on glancing collisions worksheet. Solved different types of questions for different types of questions.
 * April 23, 2010**

Andrew: Reviewed the Glancing Collision worksheet. Attempted to resolve the questions that I did incorrectly at home. Liana: fixed glancing collision problems that were homework. Marlene: Reviewed Glancing Collisions and learned more about how to complete the problems. Eric: Worked on glancing collisions worksheet. Asked questions and talked to other group mates in regards to the project.
 * April 26, 2010**

Eric was absent today. As a group, Marlene, Liana, and Andrew started the Measuring Crush Energy Lab. Andrew: Worked on Calculations for the Lab; Began excel sheet. Will complete/collaborate with group tomorrow. Liana: Started calculations for Crush Energy Lab. Marlene: Began Calculations for Crush Energy Lab.
 * April 27, 2010**

Liana: Today me and Marlene finished the Crush Energy Lab. We found that the work involved in determining the crush factor was very interesting and we learned a lot. After we finished the crush energy lab, we started determining the crush energy of our actual scenario. Overall, today was a very productive day and we got a lot done. Tonight, me and Marlene will finish our calculations for the crush energy for our scenario. Crush Energy Lab Pictures:
 * April 28, 2010

Equation: Diagram: Calculations: Typed:

CE total (C1+C2+C3+C4)= **34599.34 ft/lbs

** Andrew: Eric and I worked on the Driver Reaction Time lab. We also worked on the Drag Factor Lab. I calculated the mean of the force of pull and then determined the coefficient of friction on the asphalt. Located below is the table created in Excel. Overall, I thought that our entire group was productive and efficient at completing all the tasks at hand. Tonight I will plan out what I will discuss with my group. F.E: Find frictions produced by the two tires of the two cars, determine if or if not temperature has any effect on the crash/friction). I will also attempt to apply concepts learned from the Glancing Collision Activity to try to determine the speed of both cars before and after the crash considering how it's an inelastic, perfect collision. Given Information: Mass of Sled + 10lb block: 5.83 kg g: 9.8m/s^2 Force of Pull: Obtained through data studio graphs
 * -Our final answer for Total Crush Energy was** **34,599.34 foot/pounds**
 * -**We then used this value and the KE equation to determine the speed of the "car" that hit our "soda can." We got an answer of **467 mph. Obviously this is unrealistic; this is because the percent error was extremely high, due to the soda can technique.

Sample Calculation (shows what excel did):
 * Average Coefficient of Friction of: 0.71**

Marlene: Today Liana and I finished the Crush Energy Lab together. Also, we began to apply the knowledge we learned during the lab to the car crash itself. We began setting up calculations to determine the total crush energy and velocities of the two cars. After school, I finished the calculations for MV1 crush energy. Eric: Caught up on what I missed. Reviewed crash scenario. Worked on Drag Factor and Reaction Time lab with Andrew (I mainly worked on Reaction Time).


 * April 29, 2010**

=
Andrew: I helped Eric in performing the necessary trials for the Reaction Time lab. Then, I resumed the calculation from the night before. As an attempt to solve the crash scenario, I disregarded the 15 degrees incline and solved the problem as if it was the same problem as problem #3 from the glancing collision worksheet. Tonight I will finish the calculations and ponder over whether the 15 degree incline has any effect on the calculation. Furthermore, I will work on the progress report #1.=====

=To Liana and Marlene- don't worry about the progress report. I already posted one for us. I pretty much completed the calculations for our crash, but I'm not really sure if they're right or wrong. It's probably wrong because I didn't consider the crush stuff that you guys did. We'll figure it all out tomorrow.. and hopefully finish most of the stuff.= Marlene: Here are the Crush Calculations for MV1, the Toyota Camry. Here are these calculation typed: Liana: Today me and Marlene finished our calculations for the total crush energy for our scenario. MV2 (Honda Civic Hybrid)

Typed Calculations:

C1+C2+C3+C4+C5= **42743.175 ft/lb** Marlene: Liana and I continued working on the calculation for the total crush energy for the car crash. Again, we still are ending up with low numbers. Eric: Completed Reaction Time Lab. Produced tables for PRT of Andrew and Eric. Compared Results to results of other group and the average human PRT. Very satisfied with results.

Andrew: I emailed Detective Andy regarding some questions I had about the crash. Hopefully he responds to clear up the confusion. Liana: Reviewed ELVA book and continued to try to solve for initial velocities of both cars. Marlene: Today I continued to try to figure the initial velocity of the two cars. Andrew and I reviewed the Edhead's activities for ideas. Eric:I reviewed my crash scene and jotted down notes that would help me as my role of Policeman.
 * April 30, 2010

****May 2, 2010** Andrew: I worked with Marlene in finding the initial velocity of both cars involved in the crash. I used the information obtained through the crush calculations. Here are the calculations. By first finding the final velocity upon the perfectly inelastic collision, I was capable of finding the initial velocity of both cars upon impact. This allows us to find the initial velocity of each car before impact as well.

Calculation typed: The final velocity of the Toyota Camry and the Honda Civic upon collision (perfectly inelastic): **29.13 mph

Calculation typed: The initial velocity of the Camry prior to impact: ****39.29 mph**

Calculation Typed: The initial speed of the Civic prior to impact: **44.29 mph**

From collision to the final location: **2'' or 40 ft
 * Length of the skid marks:
 * Length of the skid marks: 2 13/16'' or 56.25

I also got some pictures of our crash scene through google maps. Crash Scene Pictures







**

Marlene: Today, Andrew and I worked to figure out the post-collision speed, the initial velocities of both cars upon collision, and the speed of MV1 before the collision. These are the calculations for the initial velocity of MV1 Picture posted by Andrew because I had technological difficulties: Here are these calculations again, but typed. Liana: Reviewed calculations worked on by Andrew and Marlene. Put together information and attempted to make my case. I will be the prosecutor on Wednesday. Eric: Looked at calculations. Updated excel chart.

Andrew: I also calculated the Toyota Camry's rate of deceleration. Then utilizing that rate, I figured out about how far the car would go before it came to a total stop. I kept in mind that the police report said that the driver stated that he was going around 25 mph. Thus, I used both 25 mph (low value) and 29 mph (high value) to determine whether he had enough to time to stop. If he did, it would prove that his statement was false, and that he was speeding at a much faster rate. Here are the calculations:



The above calculation determines how far the driver would've skidded before coming to a stop with an initial speed of 25 mph or 11.18 m/s. The above calculation determines how far the driver would've skidded before coming to a stop with an initial speed of 29 mph or 12.96 m/s.

Liana, here is what I wrote. This is what I was trying to explain to you guys the other day. I tried my best to explain it. From the evidence gathered at the scenario, it was evident that the driver of the Toyota Camry was applying his breaks. The ABS system left obvious skid marks 26.25 feet before the pedestrian crosswalk (or 26.25 feet before entering the square area of the intersection between Piermont and Kinderkamack). Thus, if he was going at around 25 mph, he should've had enough time to stop before going in range of the way of our client. Evidence from the scene shows that the accident happened 40 feet away from the initial start of the skids. Thus, this states that driver of the Camry was going at a much faster rate than that of what he stated. Furthermore, if he couldn't stop, how was it that he began to apply his breaks fully, 26.25 feet before the actual intersection? Is it because he saw that he was approaching a red light? That is all.