7P2

=Prosecution for Case #2: =

Steph Corvo, Chris DelRosso, Joe Setola


Stuff Joe did

Photos of the scene:


Calculating the Coefficient of Friction: The Coefficient of Friction is calculated by using the following equation: The Coefficient of Friction is .76. This number is rounded down from .767 to give the driver the benefit of doubt.

Trial 1: 22 cm = 50 – 22 = **.28 m** Trial 2: 21 cm = 50 – 21 = **.29 m** Trial 3: 24.5 cm = 50 – 24.5 = **.255 m** Trial 4: 23.5 cam = 50 – 23.5 = **.265 m** Trial 5: 28 cm = 50 – 28 = **.22 m** Trial 6: 27 cm = 50 – 27 = .**23 m** Trial 7: 24 cm = 50 – 24 = **.26 m** Trial 8: 18 cm = 50 – 18 = **.32 m** Trial 9: 17 cm = 50 – 17 = **.33 m** Trial 10: 21 cm = 50 – 21 = **.29 m**
 * __Reaction Time Lab__**

Y = Vot + .5gt^2 t = √(y/4.9) Trial 1: .239 seconds Trial 2: .243 seconds Trial 3: .228 seconds Trial 4: .233 seconds **Average reaction time: .236 seconds** Trial 5: .212 seconds **PRT = .236 x 10 = 2.36 seconds** Trial 6: .217 seconds Trial 7: .230 seconds Trial 8: .256 seconds Trial 9: .260 seconds Trial 10: .243 seconds

=Analyzing the Crash= Skid marks from MV1 are **13.75** ft and **8.75** ft. The average of the two is **11.25** ft. Skid marks from MV2 are **12.5** ft and **8.75** ft. The average of the two is **10.625** ft. The Drag Factor of the road surface was **.76.** The cars came to rest a distance of ~22.5 ft
 * __Preliminary Data__**

__Crush Energy__ Wheelbase = 99.4 inches A = 259 B = 43
 * __MV1 Damage Profile (2002 Subaru Forester)__**

C1 = (259^2 / 2*43) * 1 + 259 * 16 * 1 + (43 * 16^2 / 2)(1) C1 = 10,428

C2 = (259^2 / 2*43) * 1 + 259 * 21 x 1 + (43 * 21^2 / 2)(1) C2 = 15,701

C3 = (259^2 / 2*43) * 1 + 259 * 15 * 1 + (43 * 15^2 / 2)(1) C3 = 9503

C4 = (259^2 / 2*43) * 1 + 259 * 15 * 1 + (43 * 15^2 / 2)(1) C4 = 9503

C total = 45,135 feet per pound or 61,189 Newton per meter

Weight = mass * gravity Weight of Subaru Forester = 3,153 pounds 3,160 = m x 32 feet per second per second 98.8 **slugs** = mass 98.8 slugs x (14.59 kilograms / 1 slug) = 1441 kilograms

KE=Crush Energy 1/2mv^2=61,189 1/2(1441)v^2=61,189 vi=9.2 m/s vi=20.568 mph

Conclusion: The 2002 Subaru Forester was traveling at roughly 20.56 mph directly before the crash.

KE=Crush Energy + Ffd 1/2mv^2=61,189+(umg)d 1/2(1441)v^2=61,189+(.76)(1441)(9.8)(3.43) vi=11.66 m/s vi=26.067 mph

Conclusion: The Subaru Forester was traveling at 26.06 mph prior to slamming on the brakes.

Delta Vi- 26.06 mph+20.56 mph= 46.62 mph This means that MV1 lost 46.62 mph during the whole situation. Since the car lost all of this speed the car must have been moving as fast as, or probably faster than, this speed.

Wheelbase: 103.9 inches A = 173 B = 57
 * __MV2 Damage Profile (2005 Ford Focus)__**

C1 = (173^2 / 2*57) * 1 + 173 * 8+ (57 * 8^2 / 2) C1 = 3471

C2 = (173^2 / 2*57) * 1 + 173 * 18 + (57 * 18^2 / 2) C2 = 12,611

C3 = (173^2 / 2*57) * 1 + 173 * 20 + (57 * 20^2 / 2) C3 = 15,123

C4 = (173^2 / 2*57) * 1 + 173 * 12 + (57 * 12^2 / 2) C4 = 6,443

C5 = (173^2 / 2*57) * 1 + 173 * 9 + (57 * 9^2 / 2) C5 = 4128

C total = 41,776 feet per pound or 56,638 Newton per meter

Weight = mass * gravity Weight of Ford Focus = 2,621 pounds 2,621 = m x 32 feet per second per second mass = 81.9 **slugs** 81.9 slugs x (14.59 kilograms / 1 slug) = 1,195 kilograms

KE=Crush Energy 1/2mv^2=61,189 1/2(1195)v^2=61,189 vi=9.74 m/s vi=21.77 mph

Conclusion: The 2005 Ford Focus was traveling at roughly 21.77 mph directly before the crash.

KE=Crush Energy + Ffd 1/2mv^2=61,189+(umg)d 1/2(1195)v^2=61,189+(.76)(1194)(9.8)(3.24) vi=11.96 m/s vi=26.73 mph

Conclusion: The Ford Focus was traveling at 26.73 mph prior to slamming on the brakes.

Delta Vi- 26.73 mph+21.77 mph= 48.5 mph MV2 (Ford Focus) lost 48.5 mph during the event. The driver lost all of this speed meaning that the car was moving as fast, or faster than, 48.5 mph.

=__STUFF STEPH DID__=

=
-4/22: Today I downloaded the sections of the ELVA book. My job is the prosecutor, so I will read some of each section to get an idea of which questions I will be asking each of the witnesses. =====

=
-4/23: I was absent this day (Pennsylvania for a college visit) and let my group know of my absence beforehand. They learned about glancing collisions in class while I worked on preparing my questioning over the weekend. =====

=
-4/26: Today we went over the glancing collisions in class. We mainly focused on 4 and 6, which I began to understand after I got someone's notes from the Friday that I missed. =====

=
-4/27: Today we started the crush energy lab. We learned the process that we had to go to, and I completed all of the 'sample calculations'. Tomorrow we plan on calculating the crush energy specific to our assigned crash. =====

=
-4/28: My main job was calculating the crush energy for our specific crash. This was done while Joe was calculating the coefficient of friction and Chris was working on the reaction time lab. All roles were delegated so that we could get as much done in class as possible. =====

=
-4/29: Joe and I were both on a field trip and absent from class today. However, we were aware of the circumstances so delegated jobs the day before. Most of our calculations were almost complete, so we planned to finish them over the weekend. Joe also planned to take a trip to our crash site to gather information and pictures. =====

=
-4/30: Today involved major planning for our case. Joe found out some information that would give us a rough time, but we tried to prepare whatever argument we could think of. =====

=
-5/3: Today was very important because we found out that a few of our calculations were off because we weren't thinking of it correctly. After discussing with bb2, we tried another approach with different equations. Although Chris (AP exam) warned us he would not be there tomorrow, we plan to follow through with these new calculations. =====

=
-5/4: Chris was absent today, but Joe and I continued to fix our calculations. We learned that we needed to add the crush energies in order to get accurate velocities. Joe and I went to the library after school so that we could finish these calculations and put them on the wiki before time was up. At home, I put together our powerpoint along with final arguments to aid in our trial tomorrow!! =====