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In this issue
Nov. 20, 2009
Rabbi David Aaron: How to make every second of your life come first
Caroline B. Glick: Whither American Jewry
Nov. 19, 2009
Binyamin L. Jolkovsky: Please Listen to this Godcast (5 minutes)
Jonathan Tobin: ADL Crosses the Line with Report Bashing Obama Critics
Nov. 18, 2009
Rabbi Yonason Goldson: What Judaism has to say about the secret of the Mona Lisa's smile
JWisdom.com: The (Jewish) Dating Game with Rabbi Lawrence Hajioff (8 minutes)
Nov. 17, 2009
Steven Emerson: How Does the 4th Amendment Impact Terror Finance Investigations?
JWisdom.com: If Frank Sinatra married Edith Piaf with Rabbi Y.Y. Rubinstein (2 minutes) Life lessons from what would be regarded as the most inappropriate lyrics ever sung
Nov. 16, 2009
The Jewish Ethicist by Rabbi Dr. Asher Meir : When borrowing is stealing
JWisdom.com: Deconstructing faith with Rabbi Warren Goldstein (9 minutes)
Nov. 13, 2009
JWisdom.com Sarah's subjective reality with Rabbi Sroy Levitansky ( 6 minutes)
Caroline B. Glick: Obama's failure, Netanyahu's opportunity
Nov. 12, 2009
The Kosher Gourmet By Marialisa Calta : A sweet sweet potato treat
JWisdom.com Does God get tired? with Rabbi Harvey Belovski ( 5 minutes)
Nov. 11, 2009
Rabbi Avi Shafran: Jews and money: When anti-Semitism isn't
JWisdom.com Marriages are not made in Heaven with Rabbi Lawrence Hajioff (VERY fast 15 minutes)
Nov. 10, 2009
Michael Doyle: Author of book exposing CAIR ordered to remove supporting documents from Web
JWisdom.com If the creation so loudly shouts the existence of the Creator, why aren't more people believers? with Rabbi Naftali Brawer (9 minutes)
Nov. 9, 2009
Mark Steyn: Shooter exposes hole in U.S. terror strategy
JWisdom.com It's never too late to have a happy childhood with Sarah Chana Radcliffe (5 minutes)
Nov. 6, 2009
Rabbi Berel Wein: Choosing to hear
JWisdom.com Zero to 1/60th: How to Empower An Hour with Gavriel Aryeh Sande (7 minutes)
Caroline B. Glick The mullahs' big week
Suzanne Fields A Fallen Wall for Fallen Man
Nov. 5, 2009
The Kosher Gourmet: Three scrumptious -- but simple -- butternut squash dishes
JWisdom.com Hidden Hints: Unlocking Faith & Prayer with Rabbi Jay Yaacov Schwartz (10 minutes)
Nov. 4, 2009
Tom Hamburger and Kim Geiger: Should prayers be covered?
JWisdom.com When God played peacemaker With Rabbi Sroy Levitansky (5 minutes)
Nov. 3, 2009
Martin Peretz: Beware, Barack. Beware, Rahm. Beware, Axelrod
JWisdom.com Are you are closet idolater? With Sara Yoheved Rigler (10 minutes)
Nov. 2, 2009
Paul Greenberg: The Holocaust is now on Facebook
JWisdom.com Abraham's Strange Change With Rabbi Yitzchok Fingerer (5 minutes)
Oct. 29, 2003
Mortimer B. Zuckerman: Graffiti On History's Walls (MUST-READ!)

Jewish World Review

How airbags work

By Marshall Brain

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http://www.JewishWorldReview.com | (MCT) Imagine for a moment that you are driving your car. It's a beautiful day, and you are driving down the freeway at 60 mph. The windows are down; the radio is playing. You have not a care in the world.


The funny thing is that when you are sitting in that position, you are positioned right in front of an explosion that is waiting to happen. There is a computer in your car dedicated to that explosion - its single goal in life is to set that explosion off. And the computer is listening to a tiny sensor that in many cars is no bigger than a pea. When that sensor decides it is time for the explosion to happen, the computer will hear its tiny signal. In less than a millisecond the explosion will start. When the explosion happens, it is powerful enough to kill people, but for most people it is not deadly. Instead, it saves their life.


Welcome to the world of airbags. An airbag is an explosion designed to protect rather than to destroy.


The reason why your airbag is poised and ready to explode out of your steering wheel is because an accident can happen at any moment. For example, a car driving the other direction on the freeway could suddenly veer across the median and run into you head-on.


At the moment of a head-on collision, your airbag has about 5 hundredths of a second to react. During that time, your body is going to decelerate from 60 mph to 0 mph. The goal of the airbag is to help that deceleration happen as gently as possible.


The first thing that detects the crash is an accelerometer. An accelerometer is simply a device that can sense when something is rapidly accelerating or decelerating. Many cars use a tiny micro-machine etched out of silicon to detect the crash. But an accelerometer could be as simple as a steel ball attached to a magnet at one end of a small tube. During a crash, the ball breaks free from the magnet and hits two metal contacts to complete a circuit. The airbag control computer gets a signal from the accelerometer. Most cars have four or five accelerometers, and the airbag computer wants more than one of them to send a signal to be sure it is not a false alarm. Once the computer is satisfied that this is the real deal, it starts the fireworks.


What happens next is rather amazing. Inside your steering wheel is a bag made out of a fabric like nylon. There is also a metal canister called an inflator that contains sodium azide. Sodium azide is a highly reactive chemical that is very much like the fuel in a solid rocket engine. The signal from the computer fires an igniter, which lights the sodium azide. The sodim azide reacts incredibly quickly and it produces a huge cloud of hot nitrogen exhaust gas. That gas goes straight into the nylon bag. The bag inflates in a few milliseconds, with the front of the bag bursting out of the center of the steering wheel at 200 mph. This 200 mph piece of fabric is heading straight for your face.


The reason why it is heading for your face is because, if you think about it, your head is the most important thing to protect in this collision. Your torso is held in place by the seatbelt, but your head, attached to your spindly little neck, weighs as much as a bowling ball. This bowling ball contains your brain. Your brain is pretty fragile and it is still moving forward at 60 mph. The idea behind an airbag is to slam the piece of nylon, backed by a jet of nitrogen gas, into your head at 200 mph. That way, your head slows down to zero MPH as gently as possible. The airbag also takes a big load off your neck. Without an airbag, your neck has to take all the stress of bringing your bowling ball head to a stop.


So think about this the next time you are driving down the road. Sitting in front of you is your own personal explosion, connected to its own explosion-control computer. Around your car there are a number of hidden collision-sensing accelerometers. All of this equipment is sitting there quietly, waiting to bring your bowling ball head to a stop in 5 hundredths of a second, should the need ever arise.

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Previously:


How the U.S. income tax works
How gum works
How caffeine works
How Daylight Saving Time works
How a cruise missile works
How snow making works

© 2007, How Stuff Works Inc. Distributed by McClatchy-Tribune Information Services.

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