Threaded Mode | Linear Mode

zps2004 · 10-16-2011, 05:28 PM

Note to everyone out there. Be safe.

http://www.youtube.com/watch?v=6dI5ewOmHPQ

Theodore · (This post was last modified: 10-16-2011 09:56 PM by Theodore.)

Hello all...

Interesting Zach brought this up. I am working as an instructor for a Teen Survival Training in the next month. I was going over info and training courses. Two things really jumped at me :

1.) For part of training, they get an 18 wheeler to park on the lot and place 4 small cars around it (Minis, miatas, etc.). One sideways up front close to bumper, one sideways at rear of trailer. One on right beside cab and one on left. They then put students in the cab and they realize they cannot see a single one of the cars. Freaks them out. Lots of trucks have decals that read "if you can't see my mirrors I can't see you." They aren't kidding. Remember, it's not important who is right or wrong, if you are dead.

2.) Feet on the dash - there are a number of documented cases of passengers with feet on dash, someone pulls in front or slams on brakes in front of them... usually relatively slow speed accidents... but the air bag went off and drove the passenger's knees in to their body breaking jaw, breaking clavicles, breaking humerus, dislocating hips... and even killing passengers. A great safety belt will not work when your butt is in a position to put your feet on the dash... and the air bag is an "onboard landmine" aimed at your ass. Feet on dash is fun, nice to get some tan on your legs... feel the warm sun on your feet... and a great way to really mess yourself up.

Belts and airbags are life savers but when used improperly, can seriously injure or take your life.

[Image: dec10_feet_dash.ashx]

Food for thought. Hate to see this happen to any of you or any you love.
Ted

HKYStormFront · 10-16-2011, 06:56 PM

scary

**Mr.Rauq** · 10-16-2011, 08:07 PM

BMW had a mini performance driving school/teen safety school in the parking lot of a dog racing track in Houston that I went to in the summer of 09. We did skid pad and emergency lane change and ABS turns but the thing that stuck with me most was the setup they had like that with an 18 wheeler with 5 5ers parked around it. It was ridiculous to compare what you could and couldn't see with what you were expecting beforehand. Then they took the truck up to 30 in the parking lot (empty) and did a panic stop. Thing is, it didn't look like a stop. Bottom line is versus a truck, you always lose.

Legs/feet/knees on dashboards have always bothered me too. The same force that is supposed to stop you from becoming a part of the dashboard will turn your tibia and fibula into projectiles just as easily...

**karlyew** · 10-17-2011, 03:03 PM

(10-16-2011 06:46 PM)Theodore Wrote: 2.) Feet on the dash - there are a number of documented cases of passengers with feet on dash, someone pulls in front or slams on brakes in front of them... usually relatively slow speed accidents... but the air bag went off and drove the passenger's knees in to their body breaking jaw, breaking clavicles, breaking humerus, dislocating hips... and even killing passengers. A great safety belt will not work when your butt is in a position to put your feet on the dash... and the air bag is an "onboard landmine" aimed at your ass. Feet on dash is fun, nice to get some tan on your legs... feel the warm sun on your feet... and a great way to really mess yourself up.

I've actually seen this in the ER...especially when it's late and people are on road trips. A simple wreck turns into a long ER visit and possible surgery. No fun. Plus feet marks on the dash/windows are nasty.

**Mr.Rauq** · 10-17-2011, 03:13 PM

That and glare on the windshield at night from oils from peoples' feet... Not only is it blinding and annoying, it's just gross.

***jedimario*** · 10-17-2011, 07:09 PM

If you are driving a Focus that fast...

**Mr.Rauq** · (This post was last modified: 10-17-2011 08:57 PM by Mr.Rauq.)

(10-17-2011 07:09 PM)jedimario Wrote: If you are driving a Focus that fast...

...it is the same as driving 60 headfirst into an 18 wheeler going 60 in the opposite direction? Or something like that. Maybe closer to 70 each way given that the 18 wheeler will yield *a little bit*

I had to think about it for a minute too lol

straight four · 10-18-2011, 06:53 AM

See I thought the same thing, (I posted on the youtub video)

I am uber confused but to me cons of momentum says teh same thing. 60+60=120 mph crash.

search the web and you get a completely different answer.

Theodore · 10-18-2011, 07:33 AM

I think the key is deceleration. If you hit a wall at 60... you decelerate from 60 to zero in X amount of time. IF you are going 60 and you hit another car head on going 60, the deceleration is the same as hitting the wall at 60. The only difference is the weights in the vehicles (as one may move further forward on impact) and the body design and materials (as one may give more than another).
There are people WAYYYYYY more qualified than me to speak on this ... where's our engineers when we need them? ; )

wrc_fan · 10-18-2011, 08:03 AM

(10-17-2011 07:09 PM)jedimario Wrote: If you are driving a Focus that fast...

I'm pretty sure physics doesn't care what kind of car it is Wink

***jedimario*** · 10-18-2011, 08:09 AM

You're all thinking it, stop being so serious Tongue

I think it's no surprise that the car reacted like that, and wouldn't be a surprise if any car reacted that way given it hit an object that fast that didn't give at all.

**Mr.Rauq** · 10-18-2011, 12:45 PM

Let's supposed an 18 wheeler weighs 40,000 lbs- half the typical maximum allowable weight. And a Focus weighs 4,000 lbs, for the simplicity of the maths (generous, of course, in favor of the Focus). Traveling 60 mph, the 18 wheeler has about 3,520,000 foot-pound/second momentum, while the Focus has 352,000 foot-pound/second. Given that they're opposite and they stick together when they hit, and conservation of momentum and all that good stuff, it'll have about 3,168,000 foot-pound/second momentum in the direction the 18 wheeler was moving, which sets the new 18 wheeler/Focus combine about 49 mph. So not quite 120-0 in a split second, but given the assumption that the impulse is at least similar, a crash from 110 would be a bit more like hitting the 18 wheeler. Give the 18 wheeler a bit more speed and you get closer to the brick wall, although a brick wall won't drag a Focus along the road and potentially run it over.

**Clemsons2k** · 10-18-2011, 12:48 PM

Not surprised by the damage, but its still shocking.

Like Karlye I'm a BIG hater of people putting feet on dashes and windshields. Mostly cause its just freakin' NASTY, but also because you are screwed if you get into a wreck like that. I'd prefer not to eat my knee caps idk about you.

[Image: feet.jpg]

**stevebullitt** · 10-20-2011, 11:10 AM

Crazy vid

Ted hit the nail on the head. It's all about the transference of energy in a crash. 2 cars a equal weight hitting head on at 60 is the same as one hitting a wall at 60, which seems counterintutive, but remember you've got 2 times more velocity so you also have 2 time the total decleration, but 2 times as much mass as well, so it's the same. If you have more mass, you will crush what you hit. It's for this reason that driver to driver a truck is less expensive to insure than a car. You're less likely to be injured or killed in something more massive.