I'm in the hospital after car accident. Questions about G's

You got a free hood ornament, so there’s that.

You noticed that too? Amazing that pine cone!

Seat belt almost certainly but small cars can be surprisingly strong. A couple months ago I saw a BBC program where they wound up running a SmartCar – with a titanium cage – into a block of concrete at 70-mph. It was one of those worst case scenarios where the block ended at the mid-point across the car’s front so you got a lot of sheer.

The presenter was standing by the remains and said, “Now, we’re not meaning to imply you could survive running into a wall at 70 miles per hour, but the titanium worked.” He opened the door then closed it again. “It won’t be because the cabin collapsed.”

I had a huge bruise diagonally across my torso. I went swimming perhaps a week later and it still drew stares. Wear your seat belts, folks!

:eek:

Good crumple zone, that!

2009 car would have decent crumple zones. Assuming a central head-on collision (worst case), the interior of the car experienced about 120g of deceleration.
The airbag adds another 40-50cm of travel for your body though, reducing your head and torso g-force down to about 45g, with a nice even distribution of pressure over the airbag area.

This is survivable, and you should not have broken ribs, back or skull. Back dislocations likely, bruising both surface and internal guaranteed. Concussion very likely, but also most likely mild.
Your limbs, not being constrained by the airbag(s), would experience a good bit more violence, and bone breaks and/or dislocations and/or tendon and muscle damage is purely up to luck. Fortunately, your limbs are both more robust and less vital than the torso or head.

In short.
That you are awake, and coherent enough to type this on the day following the accident, means that you were quite lucky. Surviving the crash was expected though.

Update, after seeing photo of your car.
That was a glancing hit, reducing the impact force by about half…(by roughly doubling the distance over which the damage occurred)
So downgrade the personal G to about 30, but add a sideways twist to it. Much less bruising, more dislocations and wrenching of the spine.

It’s just struck (ahem) me that you drive on the other side of the road so that’s a driver’s side impact. :eek:

From your photo I have a few questions.

It looks like an offset frontal hit on the right side, as that’s where the bumper is pushed back the most. As it’s an offset hit that will cause your vehicle to rotate, which is what I suspect your vehicle did? The disturbed ground around the front of the vehicle suggests this happened as well. That will reduce the g’s you experienced as your vehicle has the energy to continue moving.

I also notice that your left from quarter panel, and headlight assemble, is trashed or simply missing. That’s not induced damage, so you hit something else, and I don’t know when or what. Did you hit more than one tree, or did you take out something else when you left the road?

Back to the g’s issue.

Looking at the car, from my own experience, I think you’re somewhere in the 20s for g forces, and you experienced a combination of longitudinal and lateral g’s. I’d need more information than what you have to determine what you experienced. Right now, with what’s available, I don’t think it can be calc’d.

If you really wanted to know, you may be able to get data from the airbag control module (I don’t have info at hand to say what’s recoverable from that model year). That would give you at least a delta-V for impact, and may also give you a speed at impact.

And yeah, that is a lovely hood ornament you have there.

How is the tree?

My bad, I’m thinking about delta-V (I use that more than Gs). Have to think about this a little more.

I didnt hit anything else, except I was traveling in a ditch and did hit a driveway that sent the car airborne for about 30’ (not height, but traveled length). I’m sure that hitting that sloped side of the driveway damaged the front end. A hole opened up in the driver’s floor and I’m wondering if that happened at the driveway or at the tree.

Apparently trees are built better than cars! There is a large piece of bark missing where the car hit, but other than that it seems okay. It was an old pine tree, about 40’ tall and pretty large around where I hit.

And if you look at the photo of the Mazda, it appears the tree claimed victory and gently set a pine cone upright in the hood!

It’s waiting for someone to ask so it can say “you should see the other guy”.

That’s how I read it as well.

While a larger car will still protect you in most instances than a smaller car, I can personally attest to walking away from a head-on collision - in a Honda Civic.

My husband was in the car as well - some kids in a Chrysler LeBaron were taking a turn a little too fast on rain-damp roads, and crossed the center line. We all walked away.

My husband survived another accident in that Civic - a 4-car pileup that totalled 3 of the 4 cars.

I imagine the “smoke” was from the airbag - a common mistake.

And a cautionary tale: When you’ve been in an accident like this, Do NOT MOVE UNLESS YOUR LIFE IS IN IMMINENT DANGER. Had Obbn’s spine been more severely inured, he could have paralyzed himself by crawling out that way. This was pounded into us rather thoroughly when I took EMT training a few decades ago.

Obbn: can’t answer your phyics question, but :eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek::eek:

Has your pain settled down enough that you can enjoy that fun, drug-free “HOLY SHIT I’M NOT DEAD!” high? That, to me, has GOT to trump any drug-based high anyone has ever felt. I was giddy. Just our luck that the cop who came to write up the report had apparently had his sense of humor surgically removed.

To nitpick: they don’t “minimize the crash” per se… your body still goes from 60 to 0, i.e. same net delta-Vee. What these things do is slow down the crash, so the (negative) acceleration is lower, hence lower G forces. Same principle of, say, dropping a glass sphere through water and through something viscous like oil. The sphere winds up on the bottom either way, bot it moves more slowly in the oil and is therefore less likely to break.

This is why highways have crumpling dividers at lane splits. You’e still gonna stop - hard - but the stopping is spread out over more time, so lower deceleration.

An article on newer car design, and safety features: Crumple zone - Wikipedia - that also talks about the different steps in slowing you down (car crumple zones, seatbelts, and innards hitting outtards (I know that isn’t a word but it ought to be!).

In addition to spreading out the deceleration time, I believe they’re designed to route the effect of the impact away from the passenger.

From Momma Zappa:
…And a cautionary tale: When you’ve been in an accident like this, Do NOT MOVE UNLESS YOUR LIFE IS IN IMMINENT DANGER. Had Obbn’s spine been more severely inured, he could have paralyzed himself by crawling out that way. This was pounded into us rather thoroughly when I took EMT training a few decades ago. "

Unless it’s an absolute emergency, stay where you are … and open a thread from in the car:D

But do put “NEED ANSWER FAST” in the subject line.