C-1

KEYNOTE: EVIDENCE

Stephanie Cha & Danny Schneider

[[image:steph&danny_scene.jpg caption="steph&danny_scene.jpg"]]
4/19/10 Danny and Steph- Completed Group Contract (Below)
 * = **Date ** ||= **Accomplishments ** ||
 * 4/19 || Completed contract (above) ||
 * 4/20 || In-class Field Trip. Self and group analysis performed. ||
 * 4/21 || We organized our group, making sure we both understood our roles, and began uploading crash scene photos and reviewing the scenario, as well as how we plan on doing our calculations. ||
 * 4/22 || Measured the skid marks and found pictures on google map for the crash. ||
 * 4/23 || Divided the work up for the weekend; finding the initial speeds of both vehicles using the length of skid marks ||
 * 4/26 || Compared our calculations ||
 * 4/27 || Crush lab: collect data ||
 * 4/28 || Worked on the calculations for the Crush Lab ||
 * 4/29 || Reaction lab, Drag Factor lab, fix Crush Lab ||
 * 4/30 || Calculations to find the speeds of both cars, fix wiki space. ||
 * 5/03 || Finalized our calculations, added exhibits to wiki ||
 * <span style="font-family: 'Trebuchet MS',Helvetica,sans-serif;">5/04 || Organized exhibits, finished keynote presentation. ||

__POLICE WITNESS__
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= =
 * EXHIBIT B: EAST ON PIERMONT (MV1)**


 * EXHIBIT C: NORTH ON KINDERKAMACK ROAD (MV2)**

EXHIBIT D: POLICE REPORT -date& time: Sunday April 11, 2010 at 7:00 AM -the eastern approach of Piermont Ave slopes upward towards Kinderkamack Rd. with an angle of 15 degrees -temperature: 58 degrees farenheit, sunny with few clouds in the sky


 * EXHIBIT E: CRASH SCENE/SPEED LIMIT**

[[image:exhibit_e.jpg]]
Kinderkamack Rd = 35 mph Piermont Ave = 40 mph

-1999 Toyota Camry -Tag: NJH123 -Color: Grey -Tires: Michelin MR4s -Front right corner and entire quarter panel of showed heavy contact damage -Front windshield cracked -RIght front passenger window was shattered -Blue transfer paint was visible on the right and passenger side doors -RIght front tire was flat and aluminum hub was cracked
 * EXHIBIT F : MV1**

-2005 Honda Civic Hybrid -Tag: NJR456 -Color: red -tires: 4michelin hydroedge -equipped with EDR that indicates vehicle was 38.3 mph the time the driver's side airbags deployed -driver's door is crushed inward -both steering wheel and the driver's seat are displaced towards the passenger side of vehicle
 * EXHIBIT G: MV2**

__EXPERT WITNESS__
EXHIBIT I: AFTER (MV1&2)** : End of Collision (MV1&MV2)
 * EXHIBIT H:**

Vf for MV1 and MV2 = 0 mph
This value represents the speed of both MV1 and MV2, because they are attached, directly after the collision. This is the initial speed, meaning the speed attained directly after they collide. This uses both the friction due to the asphalt and the grass as the cars come to a stop. This value was then used as the final velocity for the crush energy equations, right after the collision. EXHIBIT J:**


 * EXHIBIT K: DURING THE CRASH (crush energy for mv1)**

**Crush Energy Calculations**
DURING THE CRASH: MV1 CALCULATIONS

A= 317 B = 56

[[image:final_crush_energy_for_mv1.jpg]]
=== ===

===** This represents the velocity right before the collision. In order to determine these value, we utilized the final velocity right after collision (to make up for that taken out due to the crush energy) which was found above when we found the initial velocity after the collision, meaning the velocity right after the cars collided. That value, approximately 31 mph, is here used as the final velocity right after collision, then used to determine the initial velocity, right before the collision. This value was then used as the final velocity at the end of the skid marks, to find the initial velocity of the vehicle. He was clearly speeding, a lot, nearly 20 mph over the speed limit, despite his somewhat limited view. He had a disregard for the law and was speeding. **===

**MV2 CALCULATIONS**
A= 173 B= 57

[[image:real_mv2_crush.jpg]]
INITIAL VELOCITY MV2 = =
 * EXHIBIT M: BEFORE THE CRASH (VELOCITY OF MV1)**

MV1
BEFORE: Velocity of MV1 before the crash (before skidding)

This uses kinetic energy (both initial and final because the car has velocity before and after the skids) as well as work due to friction to determine the initial speed of MV1 before the skids. This took into account the final velocity at the end of the skid marks, which in this case is the initial velocity found in the crush energy equations.

Speeds DURING the crash below, with the crush energy section

Lab: Measuring Drag Factor of a Car Tire <span style="-webkit-border-horizontal-spacing: 2px; -webkit-border-vertical-spacing: 2px; border-collapse: collapse; font-weight: normal;">__Objective:__ Determine the drag factor (coefficient of friction)

__Data:__ __ Calculations: (trial 1)__ N-W = 0 N= mg = (2kg)*(9.8m/s) = 19.6 N

T=f N=f*<span style="-webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; border-collapse: separate; font-family: arial,sans-serif; font-size: small; line-height: normal;">μ μ= T/N μ = (17.27)/(19.6) = 0.881

Slope = Coefficient of friction μ= 0.8945

Conclusion: By finding the drag factor, it'll help us find the speeds of both vehicles. This coefficient of friction will be used with the normal and friction force to find out initial velocities of both cars also. The normal drag factor of asphalt is about 0.7 and our coefficient was 0.8945, which a little higher than the average. The error could be from inconsistent speed (when pulling), not enough weight to find the drag factor. Therefore, our coefficient value was a higher but it'll still help us for our calculations.

L ab: Measuring Reaction Time

__Objective:__
Determine the reaction time of a person

__Calculations: (trial 1)__
d = (0.5)(a)(t^2) 0.12 = (0.5)(9.8)(t^2) t = 0.156 s PRT = (0.156*10) = 1.565 s

Conclusion: I thought this lab was interesting because we got to find out our reaction time by using just a ruler. It's not the most accurate way to measure the reaction time, but it gives us an idea of how a person would react in a car crash. The average reaction time for a person is about 2-2.5 s and Danny's average reaction time was 1.4 s and my average was 2.08.

__Objective:__
Estimate the Crush Energy from Damage Measurements on an aluminum soda can. The can will serve as an approximate model of an automobile.

__Materials:__
soda can, ruler, meter stick, metal ball

__Data:__
Mass= 0.066 kg

Wheelbase = 109 inches A=173 B=57

Dropped Height = 0.562 m

Height of Soda Can= 0.062 m

CE= (A^2/2B)(L) + ACL +(BC^2/2)(L) L = width of crush zone (feet) C= depth of crush zone (inches_ A & B are constants
 * Zone || Width (ft) || Depth (in) ||
 * 1 || 0.0262 || 0.039 ||
 * 2 || 0.0295 || 0.195 ||
 * 3 || 0.0311 || 0.351 ||
 * 4 || 0.0295 || 0.429 ||
 * 5 || 0.0279 || 0.371 ||
 * 6 || 0.0262 || 0.176 ||
 * 7 || 0.0164 || 0.039 ||


 * Zone || CE (ft*lbs) || CE (Nm) ||
 * 1 || 7.069 || 9.584 ||
 * 2 || 8.780 || 11.904 ||
 * 3 || 10.185 || 13.809 ||
 * 4 || 10.098 || 13.692 ||
 * 5 || 9.218 || 12.498 ||
 * 6 || 7.711 || 10.454 ||
 * 7 || 4.418 || 5.990 ||
 * Sum || 57.479 || 71.941 ||

__Calculations:__
CE= (A^2/2B)(L) + ACL +(BC^2/2)(L) = (173^2/2*57)(0.0262) +(173*0.039*0.0262) +(57*0.039^2/2)(0.0262) =7.069 ft*lbs 7.069.35581795 = 9.584 Nm

Theoretical Velocity PE1=KE2+PE2 mgh=0.5mv^2+mgh (9.8m/s)(0.562m) = 0.5v^2+(9.8m/s)(0.062m) v = 4.43 m/s

Experimental Velocity KE = W (total crush energy) 0.5mv^2 = CE (0.5)(0.066)v^2 =71.941 v= 46.69 m/s

Percent Difference 100(theoretical-actual)/(theoretical) = 100(4.43-46.69)/(4.43) = 954.63%

Conclusion: Through this lab, we were able to find out velocity by finding the amount of crush energy for a soda can. The crush energy is the amount of energy lost during a crash. First, by using the formula CE= (A^2/2B)(L) + ACL +(BC^2/2)(L), we found the crush energy. And then by using PE1=KE2+PE2, we found the theoretical velocity. Then, we compared this velocity with the experimental velocity from KE= W (total crush energy). The percent difference was 954.63%, which is a very big percent error. There is a big percent error because the tracing of the can was not precise. If we used a better tool for tracing the can, we would have better results and a less percent difference.