·
Car safety features🚙
Airbags (+on/off switch)🧑🔧
- The airbags are designed to reduce the force on the person by increasing the time the collision takes place in, or decreasing the deceleration.
- It does this when a sensor in the car detects rapid deceleration
- The air bag is deployed within 20 milliseconds
- As your face hits it, it will deflate slightly, increasing the time it takes for you to completely stop because F = (mv-mu)/t, so a longer time would result in a smaller force
- Some vehicles come with an airbag on/off switch. This useful if you are driving a two-seater, such as a pick-up truck and you are carrying a child
- In case of an emergency, the airbag won’t go off and so won’t hurt the child
Seatbelts (ELR)😇
- ELR à Emergency Locking Retractor
- Seatbelts are also designed to increase the time of stopping so the force is reduced
- The seatbelts have to adjustable so it caters to all sizes
- It works when, during rapid deceleration, you continue to move forward at the car’s speed (due to your inertia), this sudden pull on the belt causes it to jam, and so it stops
- The belt is made of slightly stretchy material, so it will increase the stopping time, bringing you to a stop slightly slower, instead of just stopping you, which will hurt
- The belt is an inverted V shape, so it holds back your hips and your chest
Seatbelts (ALR)😃
- ALR à Automatic Locking Retractor
- This has the function to lock the seatbelt position (unlike the ELR)
- It is used for securing child seats
- It is useful as it can hold the child seat firmly and during a crash, the child seat won’t move
- Belts on the child seat restrain the child, these are more like the adjustable ELR belts, with the inertia reels, which jam at rapid deceleration
In I/GCSE Physics, questions linking seatbelts, momentum and force are commonly asked so it is crucial that you know it well.
This is the end of the topic.
Drafted by Catrina (Physics)