The chemical at the heart of the air bag reaction is called sodium azide, or NaN3. CRASHES trip sensors in cars that send an electric signal to an ignitor. The heat generated causes sodium azide to decompose into sodium metal and nitrogen gas, which inflates the car’s air bags.
Table of Contents
How do airbags keep you safe physics?
Air bags. Air bags increase the time taken for the head’s momentum to reach zero, and so reduce the forces on it. They also act a soft cushion and prevent cuts.
What Newton’s law applies to airbags?
Newton’s Second Law tells us that force is equal to the rate of change of momentum. In a car accident, the driver of the vehicle will typically go from moving at around 20m/s to 0m/s in the space of less than a second.
How airbag works step by step?
The bag is triggered by a heavy weight (blue) restrained by a spring (yellow) inside the red cylinder on the right. After an impact, the weight pushes the spring to the right, opening a valve inside a pipe (turquoise) that allows compressed air to flow out from a cylinder (green) and inflate the airbag cushion.
How do airbags deploy so quickly?
They deploy quickly thanks to a special electronic chip that detects when the car has come to a sudden stop. The chip triggers an explosive which fills the airbag with gas, causing it to inflate in a fraction of a second.
Which gas is filled in airbag?
Sodium azide is best known as the chemical found in automobile airbags. An electrical charge triggered by automobile impact causes sodium azide to explode and convert to nitrogen gas inside the airbag. Sodium azide is used as a chemical preservative in hospitals and laboratories.
How is physics used in car safety?
During a collision there is a change in momentum. The force of the collision is equal to the rate of change of momentum. The safety features decrease the rate of change of momentum by increasing the time of the collision, which again decreases the force of the collision on any people within the car.
How are airbags triggered?
When there is a moderate to severe crash, a signal is sent from the airbag system’s electronic control unit to an inflator within the airbag module. An igniter in the inflator starts a chemical reaction that produces a harmless gas, which inflates the airbag within the blink of an eye โ or less than 1/20th of a second.
Why do airbags reduce injuries momentum?
Air bags increase the time taken for the head’s momentum to reach zero, and so reduce the forces on it. They also act a soft cushion and prevent cuts.
How do Newton’s 3 Laws Apply in a car crash?
How does Newton’s 3rd law play a role in collision?
Newton’s third law of motion is naturally applied to collisions between two objects. In a collision between two objects, both objects experience forces that are equal in magnitude and opposite in direction. Such forces often cause one object to speed up (gain momentum) and the other object to slow down (lose momentum).
How is Newton’s third law involved in a car crash?
When the car crashes, there is no unbalanced force acting on the person, so they continue forward (Newton’s First Law). The person moves against the seat belt, exerting a force on it. The seat belt then exerts a force back on the person (Newton’s Third Law). This causes a controlled deceleration of the person.
At what speed does airbags open?
Typically, a front airbag will deploy for unbelted occupants when the crash is the equivalent of an impact into a rigid wall at 10-12 mph. Most airbags will deploy at a higher threshold โ about 16 mph โ for belted occupants because the belts alone are likely to provide adequate protection up to these moderate speeds.
What is the chemical equation for airbags?
Based on the chemical equation 2 NaN3 –> 2 Na + 3 N2, a cup of the compound can easily produce enough nitrogen gas to fill a standard airbag, which is close to 70 liters.
How does physics explain the effectiveness of seat belts and airbags?
While the driver with an airbag may experience the same average impact force as the driver with a good seatbelt, the airbag exerts an equal pressure on all points in contact with it according to Pascal’s principle. The same force is distributed over a larger area, reducing the maximum pressure on the body.
Can airbags open without seatbelt?
Airbags are not supposed to deploy if seat belts are not being worn. This is because they can cause serious injury or even prove fatal in such deployments. This is not a failsafe mechanism though. Sometimes people bypass the system by using plugs for their seat belts to switch off the alarm.
Can you set off an airbag by hitting it?
There has to be certain speed perimeters before airbags activate. Even then, it has to be a pretty significant impact to set off an airbag sensor. Finally, if the speed perimeters were met, you would have to be very lucky to hit the front with a hammer just in the right spot to hit an airbag sensor.
How hard does a airbag hit?
When the crash sensor deploys the airbags too late, it can cause serious harm due to the fact that the passengers’ heads or bodies are now too close to the airbag when it deploys. This means that someone’s body or head is impacted by a 200-mile-per-hour airbag with up to 2,000 pounds of force.
What is the maximum pressure in an airbag?
Most high pressure air bag systems have a maximum working pressure of 8 bar/116 psi or 10 bar/145 psi.
Is airbag gas toxic?
Air bags are inflated by nitrogen gas which is produced by the highly toxic chemical, sodium azide.
Why do airbags smoke?
air bags have bents, so they deflate immediately after cushioning you. They cannot smother you, and they don’t restrict your movement. The “smoke” you may have seen in a vehicle after an air bag demonstration is the nontoxic starch or talc that is used to lubricate the air bag.
What are the physics behind seatbelts?
Step 1: Seat Belts Seat belts attach your body mass to that of a car, meaning that when the car accelerates or decelerates, you do also. Were it not for seatbelts, your body would be acted upon by Newton’s First Law independently of the vehicle.
Why do cars crumple when they crash?
Crumpling allows the vehicle to take a little longer before coming to a stop, in effect lowering the average impact force, and increasing the survival space for the belted passengers.
How does understanding of physics help you prevent injury during collision?
As every action results in an equal and opposite reaction, your speed at the point of impact (and the weight of the object you hit) will determine how much force it exerts on your car. An object light enough to move when you hit it will absorb some of your kinetic energy, thus limiting the severity of the collision.
What is the explosive in airbags?
Most airbags are inflated when the inflator unit ignites a pellet of a compound called sodium azide (NAN3), kickstarting a swift chemical reaction that fills up the airbag with nitrogen gas (N2), sending it bursting out to cushion a car’s occupants.