# Speed at time of impact

1. Mar 3, 2014

### craftylady

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.

2. Mar 3, 2014

### SteamKing

Staff Emeritus
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.

3. Mar 3, 2014

### cjl

Also, how are you getting the impact times? Those can't be calculated from the known information, unless you have some additional knowledge...

4. Mar 4, 2014

### dauto

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
5. Mar 4, 2014

### sophiecentaur

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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