Car Accident Analysis: Speed at Impact and Vehicle Specifications Revealed

  • Context: Undergrad 
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    Impact Speed Time
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Discussion Overview

The discussion revolves around the analysis of a car accident involving three vehicles, focusing on the speed at impact, vehicle specifications, and the calculations related to impact forces. Participants explore the physics behind the accident, including mass, velocity, and energy considerations, while also addressing potential inconsistencies in the provided data.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant details the scenario of the accident, providing specific vehicle masses, speeds, and calculated impact forces.
  • Another participant questions the mass of Car C, suggesting that a Nissan Sentra could not weigh 8549 kg, indicating a possible error in the data.
  • Concerns are raised about the calculation of impact times, with a participant noting that such times cannot be derived from the information provided without additional knowledge.
  • There is a critique of the significant figures used in the calculations, particularly regarding the impact force, which has an unusually high number of significant figures compared to other values.
  • One participant expresses skepticism about the ability to determine the actual force during the impact without accelerometers, suggesting that the physics involved may not be sufficient for legal proceedings.
  • Another participant emphasizes the need for expert testimony to provide credible estimates of the speeds involved in the accident.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the accuracy of the data presented, the validity of the calculations, and the feasibility of determining impact forces without specific equipment.

Contextual Notes

Limitations include potential errors in vehicle mass, unclear units for speed and force, and the lack of information on how impact times were derived. The discussion also highlights the distinction between mass and weight, which remains unresolved.

Who May Find This Useful

Individuals interested in vehicle dynamics, accident reconstruction, or legal aspects of traffic incidents may find this discussion relevant.

craftylady
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Car A was turning right
Car B was stopped at stop light.
Car B with no further oncoming traffic at the time proceeded across the intersection. Halfway across the intersection Car C T-bones Car B.
CAR B is 2012 Chevy Silverado 4X4 LTZ
CAR C is approx 2002 Nissan Sentra (I believe)
When Car C impacts with CAR B, Car B rolls onto its side, causing Car B driver to be trapped until help arrives.

Car C Nissan 8549 Kg
Velocity is 5.26
Time to impact .54 seconds
Impact Force N
166547.18518518517

Car B
• Speed at impact:6.07 m/s
• or 21.85 km/h
• time until impact:0.62 s
• Energy at impact:58496.20 joules
• Mass in kg 3175

and not including the .5-.8 of road. I calculated the impact force of Car C at 155547 divided by the mass weight of car B giving Car C the rate of speed at 52.45. just need to know if this is correct or if I missed something.
 
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Do you think it is reasonable that Car B, a Chevy 4x4 pickup, has a mass of 3175 kg, and Car C, a Nissan Sentra, has a mass of 8549 kg? That's got to be the heaviest Sentra on record.
 
Also, how are you getting the impact times? Those can't be calculated from the known information, unless you have some additional knowledge...
 
craftylady said:
Car A was turning right
Car B was stopped at stop light.
Car B with no further oncoming traffic at the time proceeded across the intersection. Halfway across the intersection Car C T-bones Car B.
CAR B is 2012 Chevy Silverado 4X4 LTZ
CAR C is approx 2002 Nissan Sentra (I believe)
When Car C impacts with CAR B, Car B rolls onto its side, causing Car B driver to be trapped until help arrives.

Car C Nissan 8549 Kg
That mass seems too high
Velocity is 5.26
5.26 what? what are the units?
Time to impact .54 seconds
Impact Force N
166547.18518518517
Everything else in this problem has three significant figures, but the force has 17 sig. figs. Something is fishy here
Car B
• Speed at impact:6.07 m/s
• or 21.85 km/h
• time until impact:0.62 s
• Energy at impact:58496.20 joules
• Mass in kg 3175

and not including the .5-.8 of road.
what is .5 - .8 supposed to mean?
I calculated the impact force of Car C at 155547
again, what are the units?
divided by the mass weight
mass and weight are two different things
of car B giving Car C the rate of speed at 52.45.
Again, where are the units?
just need to know if this is correct or if I missed something.
I don't know if it's correct. How could I, given all the things listed above that you missed?
 
Last edited:
This looks like yet another question about presenting evidence in a court case.
There is no suitable Physics to deal with this satisfactorily for any arbitrator.

There is one big flaw in all of this. No one can tell what the 'Force" was during the impact unless they had accelerometers fitted to the vehicles. dauto has already asked about the quoted time for the impact.
The only way to convince a judge is to hire an expensive 'Expert Witness' who could give some very broad estimated limits to the possible speeds involved. Anything you could present the judge with would carry no weight at all, I'm afraid.
 

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