Ok not necessarily ITR related, but my best friends Aunt (drives 2000 style Camry) was T-boned in passenger side a few days ago, knocking her car 30 feet back into a persons lawn. His grandfather was in the passenger seat and is severaly injured right now, hes going to make it but hes in alot of pain with shattered hip and collar bone and apparently some sort of internal bleeding the doctors are trying to find now.

Does anyone know enough about physics or whatever to figure out at ABOUT what speed the person woulda been going to knock a 3200 lbs car 30 feet from point of impact? Not sure you could even figure this out somehow, its a 30 mph road, and there is a slight blinde spot where she got hit, but shes a cautious driver and the Cops were saying from the looks of both cars and distance her car ended up that she had no chance to react or really avoid it because the person had to of been flying.

The real reason I am asking isn't because they are having problems with insurance or anything, his Aunt is putting herself through hell in regret and self blaim right now, when fromthe looks of everything, this person was drivign extremetly fast and wreckless. I wanted to try and figure out about what speed that had to be traveling to put her mind at ease some. Any help on the matter would be super, sorry I dont really know any more distance facts or anything, but Id try and find out if someoen thinks they can help.

 

totsie, wasnt speed determined at the time of the report? I know that is one thing that they calculate while at the scene. If not, I bet CXSHOE might know.

Edit: I am speculating just like you, but I dont think even if it was determined that they were going 45-50mph would give her ease.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by migs &raquo;</TD></TR><TR><TD CLASS="quote">totsie, wasnt speed determined at the time of the report? I know that is one thing that they calculate while at the scene. If not, I bet CXSHOE might know.</TD></TR></TABLE>

actually I don't believe speed was calculated...tho I could be wrong, but no one in his family seems to know what speed the other driver was traveling at so I dont think the officers ever did. There arent any skid marks from what I can see or I would have calculated the speed using that. All I know is that I've seen a car the size of a camry get hit at 40 from the side before and that car didn't get knocked 30 feet into a lawn and have to get the door ripped off to save a mans life. I bet this person was going 45-50 to do that kinda damage.

Your probably right, but I am just trying to help the family anyway I can right now. They are a very close family and seeing my best friend going through idiot doctors not performing the right tests, moving his grandad from bed to bed with a broken hip, putting him in lots of pain, is makign me want to help ease anyway i can.

 

Unfortunately you will never know the actual speed. The TAI, should have determined everything at the scene of the accident. Vehicle weight, skid marks, distance, type of pavement, road conditions all play a part in figuring out speed. Its been a long time since I've investigated a traffic accident, but from what you have told us, anything answered would be a complete guess.

 

yea i guess your right. the worst part is the person that was speeding had a baby in the car, they are fine, but how dumb would you be to be driving 20 over the speed limit with your child in the car? I don't get people.

O well, thanks for the input guys. Mods you can erase if need be.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by totsie7944 &raquo;</TD></TR><TR><TD CLASS="quote">
Does anyone know enough about physics or whatever to figure out at ABOUT what speed the person woulda been going to knock a 3200 lbs car 30 feet from point of impact?</TD></TR></TABLE>


yes it is, when i did A-level physics a few years ago we calculated this sort of thing, unfortunately i can't remember ANY of it now


however for a car of that weight to be knocked 30feet laterally, against the direction of the tyres 30mph doesnt sound fast enough

 

You have to take into effect the coefficient of friction and the mass of the other vehicle.

It has been too long since I had physics. I'll give it a shot. Someone correct me if I am wrong.

u = static coefficient of friction on dry pavement, 0.7
N = normal force, acceleration of gravity x mass of vehicle (3200 lbs = 1451.5 kg)

F = uN = (0.7)(9.8 m/s2)(1451.5 kg) = 9957.3 (minimum force needed to move the stationary car)

------------------------------------------------------------------------------------------------

d = 9.14 m (30 ft)

W = fd = (9957.3 N)(9.14 m) = 91009.6 J

------------------------------------------------------------------------------------------------

Assuming the other vehicle weighs 3500 lbs (1587.6 kg)

W = change in kinetic energy = 1/2mv2
91009.6 J = 1/2mv2
182019.3 J = (1587.6 kg)v2
v2 = 114.6 m2/s2
v = 10.71 m/s ~ 24 mph

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlueIntegraBoy &raquo;</TD></TR><TR><TD CLASS="quote">

Assuming the other vehicle weighs 3500 lbs (1587.6 kg)

W = change in kinetic energy = 1/2mv2
91009.6 J = 1/2mv2
182019.3 J = (1587.6 kg)v2
v2 = 114.6 m2/s2
v = 10.71 m/s ~ 24 mph


</TD></TR></TABLE>


your calcs look vaguely familiar, and as long as they're right then it seems ok


not as much force as i thought


however if they braked before impact then they were going even faster....

hope the guy in hospital recovers ok soon

 

Yeah, but we have to now account the kinetic friction of the tire/pavement and tire/grass. Too many variables and 1 yr of calculus-based physics isn't going too help much.

 

haha thanks for trying man. No worries, but your calculation does look reallly familiar. Its just been 6 years since I've done physics.

Thanks for the good wishes guys. Im sure hell be ok

 

this seems to be what you're looking for, but good luck understanding it. it's been way to long since I've thought about this stuff, so my head hurt about 1/3 of the way through this page...
http://www.doe.virginia.gov/Di....html

 

there are a lot of variables that need to be considered such as was the car at rest or in motion when it got hit? if it was moving how fast? was the collision elastic or not? etc. U12+KE1+PE2=KE2+PE2 (conservation of energy) is a useful equation for problems like this.

 

i'll ask my physics teacher tmrw. what was the other car? so i know the mass of both cars.

and btw, what direction did the two cars head in? say like NW, NE, etc.