1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Speed at time of impact

  1. Mar 3, 2014 #1
    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

    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.
  2. jcsd
  3. Mar 3, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    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 gotta be the heaviest Sentra on record.
  4. Mar 3, 2014 #3


    User Avatar

    Also, how are you getting the impact times? Those can't be calculated from the known information, unless you have some additional knowledge...
  5. Mar 4, 2014 #4
    That mass seems too high
    5.26 what? what are the units?
    Everything else in this problem has three significant figures, but the force has 17 sig. figs. Something is fishy here
    what is .5 - .8 supposed to mean?
    again, what are the units?
    mass and weight are two different things
    Again, where are the units?
    I don't know if it's correct. How could I, given all the things listed above that you missed?
    Last edited: Mar 4, 2014
  6. Mar 4, 2014 #5


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook