The "This Might Be A Stupid Question, But...." Thread

[Virg]

Mental Magpie wrote:

"Virg, the car will go forward and so will you when you're struck from behind.  The seat is connected to the car and you're in the seat.  Your body is thus not independent from the car.  I don't know about the energy transfer up the leg because I think we're all imagining that part a little differently."

Your body is indeed independent from the car at the moment of impact.  The separation of you and the car is what makes pressing the brake non-dangerous.  When the car is struck from behind, it begins moving forward, but your body doesn't start moving with it until your standing intertia is absorbed by the seat cushion, which is compressed as it presses against you.  During that time, the brake pedal is moving away from you, and then your body accelerates to match, but you're not firmly in contact with the pedal so there's no opportunity for the impact energy to transfer "up your leg" in any way.  Unless you're hit from behind with a substantial amount of energy, the whole thing will be over before you meet up with the bottom range of the brake pedal anyway.  The only way the energy of an impact could be delivered through a foot pedal to your hips is if you were bearing the pedal down as hard as possible with a locked knee and the car was struck from the front.

artk2002 wrote:

"On putting the car into neutral at a stop: I was taught that it was a bad idea because it makes it easier for you to be pushed into an intersection if you're rear-ended. Having the car in gear means that the engine's inertia will keep you from moving as far."

If your foot is on the brake, then the engine drag is extremely minimal because the brakes exert thousands of times more stop load than any transmission.  Any impact capable of overwhelming the brakes will drive the car forward in a skid anyway since any car that can't exert more stopping power on its wheels than the tires exert on the road would be extremely unsafe to drive (antilock brakes exist specifically because brakes can easily stop the tires before the tires can stop the car).  If you're at a dead stop and you've got your foot firmly on the brake, you're providing all the stopping power your car is going to offer no matter what you're doing with the engine, and a collision sufficient to make engine braking relevant will destroy the back end of the car and the transmission as well.

Virg

[Ceallach]

On that subject, my own "this might be a stupid question, but": Why do so many people in America learn to drive from their parents rather than using a qualified driving instructor? It seems to me like parents would simply pass their bad habits on to the kids. I've always wondered this when reading threads about terrible drivers.

I get the impression that 'Drivers' Ed' is class based.

Driver's Ed is expensive. Some people pony up the money anyway, since some insurance companies will give you a break on new driver insurance if you have it. And some schools offer slightly cheaper classes to their students.

But a lot of teens figure they can drive just fine, so they don't need it, right? And the parents also figure they are good drivers, so they can teach their teens just fine, right? And thus the Special Snowflakery is passed down to the next generation.

My mother was taught to drive by her Dad and her brothers, who were all sure they were great drivers.    She didn't have the greatest driving record - not terrible, but there were a couple of occasions of reversing into other drivers (carpark incidents etc).    When my brother and I learnt to drive we were living in a different country where there was a cool insurance scheme whereby ALL new learner drivers got 12 paid professional driving lessons for free, and in exchange got their license 6 months faster than it would usually take - so pretty much win-win!     We both took the professional lessons. 

Cue the next time we're in the car with my mother, she changes lanes, we both exclaim "Mum! You didn't check over your shoulder!"  .... yep, turns out her Dad and brothers somehow missed that step.  She thought she could rely on mirrors.   Explains all of those minor accidents from when we were kids.  (Which again, while not terrible, were still extremely stressful childhood memories.  She had to go to court for one of them and it was quite upsetting for us!)

My point is that I agree completely - training should be from professionals, because they can ensure the correct items are all 'ticked off' and covered, rather than just a general feel for whether the person is driving ok or not. 

[Shoo]

Our kids in Washington state can't get their license until they've taken and passed a DE course.  They aren't cheap, but neither is driving a car.  If you can't afford the class, how are you going to pay for a car, gas, and insurance?

[Ceallach]

Our kids in Washington state can't get their license until they've taken and passed a DE course.  They aren't cheap, but neither is driving a car.  If you can't afford the class, how are you going to pay for a car, gas, and insurance?

I know where you're coming from, but I always find that logic quite odd to be honest.   

Money is a finite resource, so most people I know would be more likely to think  "If I do pay for the class, I won't have enough money for a car, gas and insurance, I'll save money by getting lessons from family".     Having money for 1 thing actually means less money for everything else.

[Shoo]

Our kids in Washington state can't get their license until they've taken and passed a DE course.  They aren't cheap, but neither is driving a car.  If you can't afford the class, how are you going to pay for a car, gas, and insurance?

I know where you're coming from, but I always find that logic quite odd to be honest.   

Money is a finite resource, so most people I know would be more likely to think  "If I do pay for the class, I won't have enough money for a car, gas and insurance, I'll save money by getting lessons from family".     Having money for 1 thing actually means less money for everything else.

I see it like this.  Cars and driving cost money, starting with Driver's Ed.  If you can't afford the required class, how are you going to pay for the rest of it?  It's like deciding you're going to buy a car, but skip the insurance.  I know some people DO that, but it's not smart.

[Diane AKA Traska]

Our kids in Washington state can't get their license until they've taken and passed a DE course.  They aren't cheap, but neither is driving a car.  If you can't afford the class, how are you going to pay for a car, gas, and insurance?

I know where you're coming from, but I always find that logic quite odd to be honest.   

Money is a finite resource, so most people I know would be more likely to think  "If I do pay for the class, I won't have enough money for a car, gas and insurance, I'll save money by getting lessons from family".     Having money for 1 thing actually means less money for everything else.

I see it like this.  Cars and driving cost money, starting with Driver's Ed.  If you can't afford the required class, how are you going to pay for the rest of it?  It's like deciding you're going to buy a car, but skip the insurance.  I know some people DO that, but it's not smart.

I think that classes should be mandatory (but in school), but it's like this:  You have $X  Lessons cost $Y.  That leaves you with $(X-Y).  If car = $Z, and $Z<X, but $Z>(X-Y)...

[Iris]

perpetua wrote:

"That sounds like terrible instruction. In the event of a rear end collision all the force of the accident would be transferred up your leg into your hips and pelvis with your foot on the brake like that. Still, I guess they maybe weren't as aware of these things in the 70s."

I don't follow your logic here.  If you have your foot on your brake pedal and you're struck from behind, the car will tend to lurch forward, moving itself and the pedal away from you, not toward you.  More importantly, unless you're sitting such that you can lock your knee while pressing the pedal (and if you are, you're way too far from the pedals to drive safely), no impact of any kind will transfer up your leg to your hip because your knee will bend.

Virg

Virg, the car will go forward and so will you when you're struck from behind.  The seat is connected to the car and you're in the seat.  Your body is thus not independent from the car.  I don't know about the energy transfer up the leg because I think we're all imagining that part a little differently.

Your body is indeed independent from the car, otherwise we wouldn't need seatbelts, airbags etc to keep your body in position when the car suddenly moves in an unexpected direction. You WILL go forward when the car is struck from behind, but it will not be as a direct result of the impact - i.e. Car hits your car, causing your car to move forward. As an entirely separate event (from the point of view of physics) the back of your seat will hit YOU and propel you forward - and thanks to conservation of momentum there is no guarantee whatsoever that you will move forward at the same rate or for the same distance as the car.

I'm explaining it badly, but maths not physics is my area sorry. I once heard a physicist break down the number of actual impacts in a car crash (gross warning) ending with the impact of your brain on the inside of your skull. It was quite astounding and completely obvious once someone had told me about it

[kherbert05]

While I'm not a big fan of the parent driver education scheme in Texas. I have to say that Dad was able to do something my driver's ed teacher could not because of timing. I was terrified of driving on Houston Freeways. So first Dad took me out to the roads around our farm that were 55 mph, but little traffic. Once I got used to driving the speed limit, he would get up early on Sunday mornings and have me drive up and down I10 at the speed limit. Once I mastered that we would went on the exchanges from I10 to 610 to Gulf Freeway, to Southwest Freeway - again early on Sundays when there was little traffic. Then he got me used to traffic. I admit I still hate driving in Houston Traffic, but I can do it. Thing was Dad talked to the Driver's ed teacher about my fear of the freeways and how to best deal with it.

[RingTailedLemur]

Interesting.  In the UK, learner drivers are not allowed on motorways.  You have to pass your test first.

[Mental Magpie]

Re: being independent from the car. I was using very general terms and wasn't clear. What I meant was that your body will eventually move from the crash. You won't just sit there while the car moves around you without ever moving you. For a split second while everything impacts everything else, sure, but in the end you'll move, too.

[KenveeB]

Interesting.  In the UK, learner drivers are not allowed on motorways.  You have to pass your test first.

In much of the US, it's a lot harder to get anywhere without being on a highway than it is in the UK. It would be very hard to get in enough driving practice if you weren't allowed on highways.

And honestly, highways are a lot easier in terms of sheer driving skills. Smaller roads with intersections and lights and traffic coming at you from everywhere are really a lot more challenging. Highways are just high speed.

[RingTailedLemur]

Interesting.  In the UK, learner drivers are not allowed on motorways.  You have to pass your test first.

In much of the US, it's a lot harder to get anywhere without being on a highway than it is in the UK. It would be very hard to get in enough driving practice if you weren't allowed on highways.

And honestly, highways are a lot easier in terms of sheer driving skills. Smaller roads with intersections and lights and traffic coming at you from everywhere are really a lot more challenging. Highways are just high speed.

Yes, I found that to be the case when I started driving on motorways as a new driver.  I had been a bit nervous, but when I finally did it I realised it wasn't a big deal at all.

[sunnygirl]

In the UK, you have to pass a written exam on driving and road rules before you're allowed to take the actual driving test - does this happen in the US too? Where do you go to take the test, the DMV, or in school during Drivers Ed class? What about people learning to drive who aren't taking Drivers Ed?

I was always fascinated hearing about Drivers Ed. In the UK we don't have anything like that in schools; people hire an instructor via an independent driving school and all the instruction is one-on-one in the car. People are expected to buy the Highway Code and learn the theory stuff in their own time. Do you have independent driving schools, where you can phone and an instructor brings a car to your house for a lesson, or is learning to drive mostly done via Drivers Ed and relatives? I think we should have Drivers Ed, it sounds like a much more sensible idea.

[ladyknight1]

My son will be 15 in May and we are going to take him to get his learner's permit.

In his public high school, they sign up for a six week virtual driver's education class. Once they complete that, there is a manual they have to study and a written test to take before they can get their learner's permit. Once he has his permit, he will drive with adult supervision (must be over 21) until he is 16, when he can take the driving test and get his license. Florida calls it a graduated license. You go from a learner, to having a limited license (no driving from 11pm - 6 am without an adult over 21 in the car). The restrictions lessen until they are 18 and are unrestricted.

[Snooks]

In the UK, you have to pass a written exam on driving and road rules before you're allowed to take the actual driving test - does this happen in the US too? Where do you go to take the test, the DMV, or in school during Drivers Ed class? What about people learning to drive who aren't taking Drivers Ed?

I was always fascinated hearing about Drivers Ed. In the UK we don't have anything like that in schools; people hire an instructor via an independent driving school and all the instruction is one-on-one in the car. People are expected to buy the Highway Code and learn the theory stuff in their own time. Do you have independent driving schools, where you can phone and an instructor brings a car to your house for a lesson, or is learning to drive mostly done via Drivers Ed and relatives? I think we should have Drivers Ed, it sounds like a much more sensible idea.

There's also the "Show Me Tell Me" part of the test now, which (as I understand it) involves things like "Show me how to check the oil", "Tell me how you would change the tyre".  That happens as part of the practical test.  That's come in at some point over the last ten years, I think I just missed out on having to do it.

If anyone is interested in the UK test, here's what happens during it.