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Author Topic: Static on car  (Read 26214 times)

Offline mhorton

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Static on car
« on: 21/07/2006 06:20:25 »
I download your archived podcasts and listen to them on my 100 minute commute to work every day.  In one show, you incorrectly explained why one gets shocked when touching the car door.  You explained that it is the air passing over the car that generates the static electricity.  

Instead, it is your pants rubbing on the car's seat when you slide out that causes the static which generates the spark.

The dilemma is easy to solve.  If you put your hand on the metallic part of the door as you slide out of the car, you do not get shocked once you are out of the car.  This would only be true if the static electricity resides on you.  It would not be true if the static resided on the car; you would still get shocked.  It is a great way to prevent getting zapped.  If you are touching metal as you slide out, the static electricity slowly leaks out of your hand and never builds up high enough to hurt you.  Try it next time the weather is right and you'll be happy to see that you do not get shocked.

Also, if it were going from the car, through you, and into the ground, you would feel it coming out of your toes.  You do not.  Instead, it is going from you to the car and your toes are not involved.

Question: How do Betta fish (aka Japanese fighting fish)survive in a tiny fish bowl with no air circulation, no filter, and only a couple of tiny grains of food per day?  These creatures are amazing.

Again, great show and thanks.

Mike Horton
Orange County, California, USA


 

Offline daveshorts

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Re: Static on car
« Reply #1 on: 08/08/2006 18:57:05 »
I think the explanation given is certainly the standard one, and that wind blowing past things can certainly charge them up - on helecopters it is potentially lethal, which is why when people are being picked up they try and grab the cable first with a big metal hook to ground the aircraft before the person touches down.

From my childhood of climbing over electric fences you feel an electric shock much more strongly if you touch something at one point than if you are grabbing it. Grabbing the wire was fine (if a little disconcerting), but touching it gingerly hurt  like hell. This is because if you touch something with one finger all the current goes through the point contact, whereas when I grabbed the fence it was spread out over my hand so much less intense and hurts less.

 I would have thought the same thing was true of touching a car. Your feet are large so the current is spread out, but the point you are touching the door is probably small.
 

Offline cat93

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Re: Static on car
« Reply #2 on: 28/11/2006 08:15:34 »
I registered on this site to ask one specific question.  Don't laugh (although you may be tempted) Everytime I exit my car, I shock myself.  I've noticed that my by big left toe gets a shock as well.  I've also noticed that that same big left toe gathers a black substance around the toenail, but my right toe does not. 

My Question:  Is the static electric shock I'm experiencing from the car travelling through my body, exiting my left toe, and leaving powder burns there?  (Explaining the black substance around my toenail)?

Any insight would be great!
 

Offline daveshorts

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Re: Static on car
« Reply #3 on: 28/11/2006 08:44:00 »
Do you only get the black substance when you have been shocked, or is it there all the time? as one possiblility is that there is a dent in your shoe's sole around your big toe and your toe is picking up rubber dust. This would be the lowest resistance path to earth so the current will flow through your toe to the ground as you suggest. I would have thought that if it was a burn strong enough to blacken your skin it would cause whitening and possibly a blister.

 

Offline cat93

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Re: Static on car
« Reply #4 on: 28/11/2006 20:25:08 »
Thanks so much for taking time to answer my post, Dave!


You suggested a "possiblility is that there is a dent in your shoe's sole around your big toe and your toe is picking up rubber dust."  That makes sense because the sandal I've been wearing on that foot is very worn under the area where my big toe lays, and that area is very black. It's a shiny black on the leather upper surface of the sandal.  The other shoe doesn't look like that.


You asked, "Do you get the black substance when you have been shocked, or ist it all the time?"    It's tough to say since I'm in the car everyday...and I'm getting shocked everyday.  (I try to mitigate it by closing the car door with my back to avoid shocking my hand, but that shock still often zaps me in my toe.)

I also can't tell you for sure whether or not I get the black substance directly after the first shock of the morning -- or if it's a cummulative effect throughout the day.   Up until recently I had been wearing sandals or flip flops, and my toes are exposed.  Whenever I get out of my car I get a shock on some part of my hand  and almost simultaneously I get a shock on my big toe. By the end of the day just that toe has black stuff in the nail bed -- not on the skin itself.  If it had to describe it's consistency, I'd say it feels like hard chalk. (Like if you were to draw thick lines on concrete with a wet piece of chalk -- the thick lines of chalk have the same consistency as the black stuff on my toe nail bed.)

Thanks again for your time and suggestions,
--Cathy
 

Offline daveshorts

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Re: Static on car
« Reply #5 on: 28/11/2006 22:15:55 »
I would be surprised if the current is leaving your foot through your nail bed, as that would be a round about route for it to go. The shock in your hand is definitely related to the one on your toe, entrance and exit wounds as it were. The black stuff could be general grime, or skin that has worn off a while ago, or possibly something decomposing the skin whilst still on your feet...

An interesting experiment to try would be to put a piece of tin-foil under your foott in your shoe - because it conducts well it should spread the current out over the whole of your foot, and you may not feel the current leaving you. Probably not a long term solution though... a rubber insole of some kind may insulate you from the floor so reducing the size of the shock, and probably spread the current out over your foot as well...
 

Offline cat93

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Re: Static on car
« Reply #6 on: 29/11/2006 03:26:37 »
quite interesting dave,
now that the weather is cooler (in California) I'm out of my sandals and back into my Nikes -- so I' can try the "aluminum-foil-in-the-shoe" trick.  This may even be the beginnig of a science fair project for my kids! 

Thanks again for your thoughtfullness in answering my question.  I'll let you know what happens.
 

Offline mhorton

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Static on car
« Reply #7 on: 26/03/2007 07:17:06 »
"I think the explanation given is certainly the standard one"

With all due respect, Dave, it is commonly explained that the primary colors are red, yellow, and blue and that raindrops are teardrop shaped, and that flashlight batteries leak acid, and that the Earth's orbit is highly elliptical, and that salt solutions are neutral, but none of those things are true either.

A couple of things:

1) The next time you get shocked touching your car, ground the car completely.  Then get in the car and back out again.  You will get shocked.  Do it over and over again.  Do it with a car that has been sitting for weeks and you will still get shocked.

2) Touch a metal part of the car door as you get out.  You will not get shocked.

3) Get out of the car without touching it and touch a nearby grounded metal object (water pipe).  You will get shocked.

4) Take your car to the car wash.  Drive on the freeway while your car is still wet.  The water droplets on the hood of your car hardly move.  The air does not even rub against your car at normal freeway speeds.  There is a layer of turbulent air on the car's surface and the fast-moving air travels along that layer.  If this weren't true, cars would never get dusty, the dust would blow off on the freeway.  It does not.
Airplanes travel much faster than cars and have lots of slanted surfaces (wings).  Cars slow down on the freeway because of collisions between vertical surfaces (i.e.- the grill) and air molecules, not because of friction.  Friction does not increase with speed, yet resistance on your car increases with the square of your speed.  That is because the vertical surfaces on the car are colliding with 4 times as much air if you double your speed.

I'm not trying to be a smart @$$ here, but simply put, your explanation is wrong and I've given you some simple experiments to prove it.

Here's a link with the same explanation:
newbielink:http://sg.answers.yahoo.com/question/index?qid=20070105190717AAff5HO [nonactive]
Here's another that suggests putting fabric softener on your seats and carpet to stop from being shocked:
newbielink:http://www.startribune.com/blogs/roadguy/?p=207 [nonactive]
Here's another, just click on "Problems Created By Automobile Static Electricity"
newbielink:http://www.stopzap.com/ [nonactive] (funny, though that they explain it correctly and then one out of the three products wouldn't prevent this type of static)
Here are more:
newbielink:http://www.yelp.com/topic/gQu0LD8TMqEwrMYypREIkg [nonactive]
Here's one that shows that cloth seats get shocked and leather seats don't:
newbielink:http://www.tundrasolutions.com/forums/polls/63355-do-you-get-shocked-2/ [nonactive]
"bumblech" gives a spectacular explanation here about 1/3 of the way down:
newbielink:http://uk.answers.yahoo.com/question/index?qid=20070323100431AA0Qtxm [nonactive]

Extraordinary claims require extraordinary evidence so I think I accomplished that.

 

paul.fr

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Static on car
« Reply #8 on: 26/03/2007 07:42:20 »
mhorton.

As someone who gets shocks all of the time, i find it strange that one place i never get a shock is getiing out of a car.

Part of your explination is correct, but only one of many. Static build up from friction moving out of a car with nylon seat coverings is a factor. So is the clothing worn by the person, as far as i understand it, women are more prone to shocks from cars because they "tend to" wear more brightly coloured clothes which are more often made of a synthetic material thus creating more static.
 

Offline elegantlywasted

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Static on car
« Reply #9 on: 26/03/2007 23:54:20 »
I get shocked every time I get out of my car and touch the door, if I touch the door handle however, no shock... its pretty cool.

Sidenote, I went out on a date with this guy, we will call him 'NoJobNoMoney', and at the end of the night he went to kiss me, and there was a shock that lept from our noses, a completley visable bolt of electricity. I took it as a sign. Then it began to happen all of the time, every time we touched each other, there would be a huge shock. It got ridicuous, is it possible that we were negatives to each other?
 

Offline daveshorts

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Static on car
« Reply #10 on: 27/03/2007 10:23:22 »
I think the air moving over the car would charge it up if it weren't for the fact that modern tyres are slightly conductive so it isn't a problem any more
 

Offline mhorton

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Static on car
« Reply #11 on: 24/04/2007 00:02:59 »
mhorton.

As someone who gets shocks all of the time, i find it strange that one place i never get a shock is getiing out of a car.

Part of your explination is correct, but only one of many. Static build up from friction moving out of a car with nylon seat coverings is a factor. So is the clothing worn by the person, as far as i understand it, women are more prone to shocks from cars because they "tend to" wear more brightly coloured clothes which are more often made of a synthetic material thus creating more static.

paul.fr;

I agree with almost everything you say.  You are correct that it takes more than just seats.  I said that leather seats do not produce shocks.  I should have added that leather pants do not produce shocks either.  It is the two materials rubbing against each other that cause the shock.

I disagree however with "only one of many."  There may be many explanations, but this one is correct.
 

paul.fr

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Static on car
« Reply #12 on: 24/04/2007 07:47:38 »
well i am glad you only went as far as agrreing with "almost" everything i say. If you had gone the whole hog and agreed with everything i would have to question your sanity!

i am sure there are many reasons, why this happens. But you do have to factor in lots of variables for each incident. I think my previous comment was the most common.
 

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Static on car
« Reply #12 on: 24/04/2007 07:47:38 »

 

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