Rear end collision...how fast was that car going?

NYSpeed Automotive NYSpeed Off Topic
1

So 3:30am this morning, my friends Pontiac Vibe got blasted in the ass by a newer Ford Focus driven by a drunk driver. The Vibe was an automatic, in park on the street, and after it was all said and done had traveled 100’ after the impact. It had also made some contact with a tree which redirected it’s course a bit.

Now, my math isn’t what it used to be, but can anyone run some numbers and give an educated guess as to how fast this dude’s Focus was going before the impact? This is solely for my curiosity. Police report, insurance, all that shit has all been handled.

Focus 2900lbs (including driver) traveling at XXXmph = Vibe 2800lbs. relocating 100’

http://i84.photobucket.com/albums/k21/deener50/photo15_zps3a2cce20.jpg

2

did the impact pop it out of gear? like was it freely rolling afterward or was the transmission still engaged in park?

3

Didn’t notice that, nor did I see any skid marks, so who know maybe it did get bumped out of gear. The pass front tire was flat, most likely from popping the curb and hitting the tree (tree was about 40’ from initial hit).

4

It’s a Vibe. You can’t smash those hard enough.

5

Most people don’t really give a shit about what they drive.

6

Sucks they crashed before hitting that sweet ramp ahead. That always happens to me on GTA.

7

Either way it’s totaled.

This thread just for shits and giggles?

8

I’m just curious how fast a car has to be moving to shove a parked car 100’.

I don’t care about the fact my friend drove a Vibe.
He doesn’t really care that he drove a Vibe, nor does he really care that its totaled.

Aren’t there some smart math dudes on here?

9

Not on a Friday night at 10:30 All the nerds are out partying.

I would be somewhere in the neighborhood of 45-55mph based on the impact damage. I can barely add 2+2 so there is zero fact behind my guess.

10

Is this how the cars were at the end of it all? Like in this position?

11

There are a lot of unknowns, such as how much impact energy is adsorbed during the compression of crash structures, did park hold the tires locked, does park hold only one tire locked, did the rear damage “brake” the rear tires…

So we have 2900lb moving at ???mph.

After impact moved 100’.

I’m sure 6 years ago I could come up with a better answer, but as in this thread:http://www.nyspeed.com/showthread.php?234432-Bikers-you-all-ok&p=3389301&viewfull=1#post3389301 let’s assume 35 mph to see if plausible?

http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html
2900lb drunk car = 1318 kg.
Assuming 35 mph = 42 foot fall = 12.8 meters
Lands 100’ away = d = 30.48 meters

http://www.convertunits.com/from/newtons/to/lbs
Equates to an impact force of 5424 N = 1219 lbs force

Let’s assume a vehicle in park has .5g of grip (pulled completely out of thin air, but would park hold, or close to limit on a 45* hill?) So it would take Vibe 2800lb*.5 = 1400 lbs of force to start to move it.

I say faster than 35 mph.

Trying 60 mph:

http://hyperphysics.phy-astr.gsu.edu/hbase/flobi.html
2900lb drunk car = 1318 kg.
Assuming 60 mph = 121 foot fall = 37 meters
Lands 100’ away = d = 30.48 meters

http://www.convertunits.com/from/newtons/to/lbs
Equates to an impact force of 15679 N = 3524 lbs force, enough to start to move the Vibe, but enough to move it 100’ after energy is absorbed by crush panels? does the one tire holding park break free? Sliding friction is less than static friction.

Cliffs, too many variables for me. In my opinion with sloppy maths, drunk car was moving faster than 35 mph.

60 mph hitting a car of equal mass is kinda sorta close to hitting a brick wall at 30 mph. Is the damage greater or less than that?

12

http://glittermagic.files.wordpress.com/2011/04/jellybean-jar.jpg

Since we’re talking math, how many beans are in this jar?

13

1,449. Do I have to show my work?

14

Nope, because these contests are always rigged. Ain’t nobody gonna fucking count 1,449 jelly beans, you just award the prize to somebody you know.

15

Without doing any math…I would say…fast…

16

88mph.

17

Probably 87mph otherwise the flux capacitor would have kicked in

18

So glad he wasn’t in the car man! People are idiots.

19

Then you’d see some serious shit.

20

Crazy! Were there any wet leaves on the road? That would make it a hell of a lot easier to go 100 feet.