Events which seem to stretch the laws of physics

Factual Questions
1

Has anyone had anything happened to them which didn’t seem like it should, or could have? Maybe someone can try to explain this…
When I was about 17 I was driving home from dropping my sister & a friend off at the movies. It was lightly raining, and the road sloped slightly downhill. I paid a lot less attention driving back then, and I didn’t notice that the car ahead of the one in front of me suddenly slammed on his brakes to take a right turn. The guy behind him, who was a bit too close, (as I was) jammed on his own, and then I noticed…and it was my turn.
I was driving a 1979 Mercury Capri Turbo RS. The tires were worn and horrible. I didn’t find out till maybe a year later just how little traction I had, compared to virtually any other car with decent tires. I slammed on the brakes, and all 4 tires locked & the car was sliding forward, heading for the bumper of the car in front of me at about 25 mph or so - not a fatal speed, but definitely bigger than fender-bender country. I also modulate my brakes much better nowadays, but in a panic my foot simply pressed the pedal against the firewall as hard as I could. I didn’t turn my wheel - I knew it would be useless - I just sat there frozen, looking at the car ahead. When said car was maybe 4 feet in front of me, suddenly there was a huge force like a big hand shoving my car’s front end to the right. The direction my car was travelling changed 90 degrees, and I went up & onto the lawn of a house. I might add that this was the only house on this section of street that didn’t have a fence. I recovered my breath, and pulled back out & went home, my car undamaged, the only bad thing was a couple of minor tire tracks on a person’s lawn.

How did this happen? I explained it to myself as my right rear tire suddenly & inexplicably grabbing hold somehow, and the mass of the car pirouetting around it, sort of like Batman does a grappling-hook turn. I can’t imagine how this possibly could have happened…if it was a pothole, my front tire would have hit it first. I felt no bumps. If it was an unusually grippy patch of pavement, same thing - front tire has first dibs. However, it seems to me that a 2900-pound vehicle travelling at 20-25 mph would take a lot of force to change its velocity 90 degrees.

It felt exactly like a giant hand…the Hand of God? I’d really hate to think that God would take time away from more important things to save my car from a few hundred dollar’s worth of damage. I was wearing a seatbelt - I wasn’t completely stupid back then - and I doubt I would have gotten hurt, beyond maybe a bruise or a cut or something. Anyway, I’m sure from my point of view in the driver’s seat a giant hand would be tactilly indistinguishable from, say, a grappling hook on the other side.

Was it just a right rear tire being incredibly brave and competent when I needed it most? Or is there another explanation?

2

The “grippy spot hit the right rear tire” idea isn’t too bad. It may have been that when the right front tire went over that spot, the car was traveling fast enough that the grippy spot didn’t have much effect, but that you had slowed down just enough by the time the back tire got there that it grabbed. However, this grippy spot providing force in a direction opposite to your travel isn’t going to really do much to change your direction of travel. It will definitely work to rotate your car, but your momentum will still mostly be in the same direction. Granted, now that your car is rotated a little, any momentary static grip your tires get will tend to accelerate you in the direction that tire is pointed, so the overall effect can be to change your direction of travel.

Also, there may have been a slight side-grade to the road. It’s very startling how fast your car can suddenly start moving to the side when you lock up your tires on a road with a side-grade, since overcoming static friction in one direction keeps it from acting in another direction, since the surfaces are already sliding against one another.

It could even have been a combination. Imagine you were accelerating sideways a little due to the side-grade and your back tire hit an especially grippy spot that your front tire didn’t hit, forcing you to turn sideways even faster.

3

hand of god and phyics-explanations aren’t mutually exclusive

4

I think the most likely possiblity is that you experienced “Axle hop.” Your 79 Capri was based on the Ford Fairmont chassis (which remains the platform for the Mustang to this day). As such, it had a live rear axle suspension. A live rear axle suspension for those who don’t know, basically consists of a solid axle assembly joining the rear wheels to the differential. Think of the whole thing as giant T shaped piece of metal with the rear wheels at the ends of the crossbar.

Being solidly connected, each movement of one rear wheel affects the grip of the other. (As opposed to an independent suspension where each wheel is seperately mounted to the chassis.)

What can happen with these solid beam axle suspensions is that lateral force can build up in the springs of both sides as force is applied. This has the effect of “winding up” the suspension, which will snap back into place when the tension is relieved.

So if you are braking heavily, especially on an older car, the force is not likely to be even. If the wheel is turned at all, or if the brakes slow the car unevenly, lateral force will build up in your rear suspension. This could also be caused perhaps by a more grippy spot on the road.

Then as you brake harder and harder, weight is transferring off your rear wheels. At some point you reach the moment when the weight of the car over the rear wheels is not enough to keep them planted on the road against the tension built up in the springs. This is most likely caused by a bump or something that causes the rear wheels to bounce off the ground.

Once the rear wheels leave the ground, the whole rear axle with both wheels will snap back into position. When this happens it is quite dramatic.

I’ve had this happen to me a few times in my parent’s old pickup truck (same type of suspension). The whole rear end of the truck will lift off the ground and step laterally a few feet. It is quite sobering, and I imagine that something like this could easily move a small car like the capri 90 degrees, especially since the car would probably keep pivoting after it landed given the poor traction.

This sort of behavior always make me shake my head when I see jackasses driving along the highway at 80 mph in their pickup trucks. Given the lack of weight over the rear wheels and their suspension design, they are just not safe to operate at that speed.

So there you go, until someone can do better, axle hop caused it

5

I dont know any tech talk–but how about a fairly simple answer:–your car just did a standard jacknife skid.

Suppose it had been on a snowy, icy road. Would you be so surprised at your car suddenly spinning around after you locked up your brakes?
It happens all the time–that’s why they teach you in driver’s ed class not to lock your brakes when you start to skid on snow.

I dont know if a wet road with bald tires is as slippery as snow covered road , but the principle seems the same.

Also, don’t forget that your 17-year-old memory isn’t an accurate scientific description of what happened–it’s a good description of what you THINK happened. You were scared, your eyes were locked straight ahead.You weren’t fully aware of everything around you. Maybe the “Sudden force, like a hand shoving the car” was actually a gradual force- of a skidding car. Could it be that the back of the car had started skidding to the left already, and you didn’t notice because your attention was focused on the bumper ahead of you? So as the skid progressed from a 10 degree angle to 90 degree right-turn,it seemed to you like a miracle. But it could have been just the natural force of a typical skid.

6

Uh, except that he was driving a Capri, not a tractor trailer…

A “jacknife skid” is when a trailer fully articulates while skidding. Cars, not being hinged in the middle, are incapable of jacknifing.

What you are referring to is simply called a spin, or if you want the tech talk: “trailing thottle oversteer.” :wink:

It is certainly possible that he did experience TTO, but that would require that he mis-remembered, as a spin like that would require the front wheels not to have locked. (Certainly possible)

You make a good point though, that memories like this can be elusive, and what is remembered may not be what really happened.

7

Consider Wind Shear.

A brief, extremely violent, but highly localized windstorm.

It can occur even in relatively mild rainstorms, & it was raining, you know.

8

Older? That’s funny, I bought a 1979 Mercury Capri Turbo RS and it was brand new. :frowning: Seems like only yesterday. (No “geezer” smiley available.)

9

>It may have been that when the right front tire went over that >spot, the car was traveling fast enough that the grippy spot >didn’t have much effect, but that you had slowed down just >enough by the time the back tire got there that it grabbed.

The car didn’t slow down very much.

>now that your car is rotated a little, any momentary static grip >your tires get will tend to accelerate you in the direction that >tire is pointed

The tires were locked up, so I don’t think they’d have directional control.

>Suppose it had been on a snowy, icy road. Would you be so >surprised at your car suddenly spinning around after you locked >up your brakes?
>It happens all the time

Yes, I have seen many, many spinouts on icy & snowy roads, but I’ve NEVER seen this happen “suddenly”. Lack of traction doesn’t cause spinouts, incompetent driving does.

> Could it be that the back of the car had started skidding to the >left already, and you didn’t notice because your attention was >focused on the bumper ahead of you?

Very doubtful. I may not have paid much attention to traffic then, but I was a very capable driver at 17. I was a devoted reader of Car & Driver, back when it was a quality magazine. I was quite skilled at executing bootlegger’s turns, 360s (no, not “donuts”, REAL 360’s) and using the throttle to control the angle of the car through skidding turns. The car was going straight, then it was flying up onto the lawn. The sideways force was powerful enough that for a second I was looking through the driver’s door window.

It wasn’t TTO, not only were the front wheels locked, the clutch pedal was in.

10

Oh yeah, wind shear…nahh, there would have been a gust of wind…besides, this happened in an area surrounded by tall trees, tall houses, and on one side was a big hill containing the town reservoir. Besides, wind shear or microbursts can be dangerous to a plane taking off of a runway, nowhere near trees or obstructions, but a pinpoint burst that pushes a car violently?? Seems I would have read about something like that happening at some point…after all, if it happened, it would most likely happen to cars in large parking lots more frequently than to cars in sparse traffic…

I can just imagine…a car salesman at a dealership pulling out his hair upon discovering another one of those damn microbursts piled up his inventory…

11

I’m telling you dude:

Axle Hop

12

Um, I think if you’ll just read my posts again, you’ll see that it wasn’t axle hop.

13

I’m no expert, but it sounds like oversteer induced by your heavy braking. I had a semi-similar experience…Driving a buddy’s '91 Accord, speeding along, going around a wide, sweeping left-hand corner too fast, started losing traction & understeering (so now I want to be going left, car is going more or less straight), hit the brakes way too hard, and the rear of the car snaps around to the right. As it was, if I had let off the brakes then, I think everything would have been fine, but I didn’t overcorrected for the skid, fishtailed a little and put the car into a hedge…confused the hell out of the guy in the trunk, but that’s another story
Of course, since you weren’t cornering, I don’t know how applicable my little anectode is, but it sounds like a possibility.

14

I was able to approximate the effect described by the OP in a 1975 Ford Mustang once, but I did it when I was just goofing around in parking lot while it was raining and my car was in no danger of hitting anything. I’m buying the axle hop hypothesis.

Of course, if you’re determined to have someone declare that you experienced a miraculous event that saved your car from an accident, nothing that I or anyone else says is going to convince you…

15

>Of course, if you’re determined to have someone declare that >you experienced a miraculous event that saved your car from an >accident, nothing that I or anyone else says is going to convince >you…

Of course I don’t believe this, but I still haven’t heard an explanation…I think there is one, I’d like to hear it, but if I don’t find out, I just won’t know, that’s all. Is that enough commas for you? I was just hoping to get some suggestions, as well as hear any other stories other people may have to tell.

“All truth goes through three stages. First it is ridiculed. Then it is violently opposed. Finally, it is accepted as self-evident.” - Arthur Schopenhauer

16

Why is it that every odd phenomenon that does not conform to easy explanation is assumed to be the work of God? Why can’t we just say, “I don’t know why that happened”, until evidence points the way to the truth? Or are we so insecure that everything must be explained, even if it means ascribing it to the work of God, just so we won’t have to live in an uncertain world? Is certainty that important? “I don’t know” is a perfectly good reaction to events like these.

17

I’m not sure you really are willing to entertain reasonable hypotheses about what went on. “The car didn’t slow down very much” isn’t exactly a stellar counterargument, given that 1) you really have no idea how much the car slowed down in the very short period of time while you were panic-stomping the brakes, and 2) the car isn’t required to slow down very much in order to pass a threshold if it’s close to that threshold to begin with.

You also apparently feel that it’s impossible for a single tire to experience a momentary solid grip while you perceive the car as being in a full skid. Well, it’s difficult for you to tell if all four wheels are stopped or if 3 of them are skidding and one grabs the road for a fraction of a second and then lets go again when the tire gets stressed and deforms a little. When you’re near the threshold of regaining grip, the skid cannot be modeled in the same way. Some tires grip before others, and sometimes the force the road is applying to the tire overcomes the force the brake is applying to the wheel for a moment, and the tire grabs for a split second but starts skidding again almost immediately (probably since when it grabs, the stress on the tire can deform it and make it lose traction, but that’s a guess).

I’m not sure why you think the wind idea is so ridiculous. You seem to think that it would take the same force to blow a parked car across a parking lot as it would to blow an already skidding car off course. If you think that’s true, I offer you this experiment: set a book up at an angle that’s not quite enough to make a coin slide down it. Set the coin on the book and notice that the force of gravity is not enough to make it slide down the book due to the static friction. Now take a pencil and try to push the coin across the slope (not up or down). Notice that as soon as you break the static friction, the small force pushing the coin down the hill is more than enough to make it quickly head in the downhill direction.

None of us is claiming to know what happened, but we’re offering plausible factors, albeit small, which would at least contribute to what you described. That’s what you asked for, and you’re dismissing most of it with little more than a “nah, I doubt that.” Which makes me wonder what you really hoped to accomplish by asking the question. You sound as though you really do want to believe it’s some unexplainable mystery. In all likelihood, it is unexplainable, but it’s because we don’t have any accurate, detailed account of what actually went on, not because you experienced some kind of tear in the space-time continuum.

18

  1. I’m not sure if Fear Itself was referring to me, but I can’t explain why people think God is responsible for things they can’t understand, any more than I can explain why people think aliens are the only things UFO’s could be. I thought I explained myself clearly in the OP, and then I clarified, but it seems some people are still not getting it (I’m referring to ppl in general, not Fear)…I do not think any diety was responsible, nor do I think anything supernatural occured.

  2. I’m assuming most of the posters here live in the US, as do I. Driving is a poorly-understood art here, and most people don’t have a basic grasp of the mechanics involved. Since I do, it’s easy for me to discard suggestions that I know don’t fit.

  3. Aside from misunderstanding my thrust, ntucker makes some good points, which I already understand…but I’ll respond to them, for the benefit of interested people.

3a. Tires & threshold…you don’t know what those tires were like. I do. It’s not that I don’t think one could have caught hold, I just think that the force required to cause the result could have been generated by one tire. On dry pavement, with warm tires, that car would skid forever from 30 mph. It was my first car, so I was unaware just how bad they were…but I found out not too much longer, before I got my second. I also practiced many high-performance stunts in that car, in parking lots mostly, and I was very familiar with handing of the car, and the feedback it generated. If a tire had caught hold, I’m pretty sure I would not only have felt it, I’d have been able to tell you which tire it was.

3b. “You seem to think that it would take the same force to blow a parked car across a parking lot as it would to blow an already skidding car off course”
No, I don’t, but I’m well aware of what the wind can do. I’m a pilot, and I deal with it all the time. A local-force wind like that could toss a motorcycle over a fence, or a bicyclist into someone’s living room. Again, I would have seen the effects of the wind. Also, I think the book analogy is not an appropriate one - this has nothing to do with static friction.

3c. "That’s what you asked for, and you’re dismissing most of it with little more than a “nah, I doubt that.” "

I don’t mean to sound snobbish or anything, I’ve just considered a lot of these already. I’m not indicating dissatisfaction with the ideas - I’m glad I got the responses - I’m just still looking. The OP wasn’t only about me, either.

“You sound as though you really do want to believe it’s some unexplainable mystery.”

Nope.

“In all likelihood, it is unexplainable, but it’s because we don’t have any accurate, detailed account of what actually went on, not because you experienced some kind of tear in the space-time continuum.”

I agree. It’s not just that an accurate, detailed account isn’t available, it’s also that there are many factors involved which are unknown, even to me, as there are in every event that ever happens.
Thank you all for the suggestions, I’m open to more.

19

Sure it does. Your wild scenario of a used car lot with all the cars pushed over to one side indicates that you’re misunderstanding what’s being suggested. When a car is skidding, it doesn’t take nearly as much force to push it sideways as it does when it’s sitting still or traveling with the tires in static contact with the road. It doesn’t seem like you understand the impact of this, and you might be startled at the huge effect if you actually try the book/coin experiment.

20

Monk, I don’t see anything in your post that would rule out axle hop… What is it that you think is so self evident that I am obviously missing that would rule it out?
I’ve experienced it many times and it produces almost exactly the set up symptoms you described.
And Ender, hitting the Brakes AT ALL was your mistake, not just hitting them too hard. When you understeer your front wheels are at their limit of grip, using it all up trying to execute the turn. If you then add braking into the mix, the tires have no traction left for braking and all you’ll do is make it worse, as you saw.

Remember: “When in doubt, both feet out” (out meaning off the pedals)