Science behind car safety features (broad, open-ended question, sorry)

In summary, the conversation discusses the topic of car safety features and their function in reducing injury during crashes. The use of Newton's Laws of Motion, Equations of Motion, energy transfers and momentum are necessary in understanding these features. The goal is to increase stopping distance and stopping time in order to reduce the force of deceleration. Seatbelts, airbags, and brakes all work towards this goal by dissipating kinetic energy over a longer period of time. Crumple zones also play a role in absorbing energy during a crash. The conversation ends with a request for further input and clarification on the topic.
  • #1
deman
2
0
Hi all, I'm new here and new to physics all together. I am taking a general science class in college (real basic stuff) and have only been focusing on physics for 1 term so I am pretty ignorant on the topic.

We have an in class assessment dealing with cars and their safety features: seatbelts(including inertia reels), airbags, crumplezones and brakes; dealing with the science behind their function. I need to refer to Newton’s Laws of motion, The Equations of Motion, energy transfers and momentum where appropriate.

I am aware that the science in car crashes is all about reducing the stopping time, both of the car and occupant and that safety features need to take the occupants kinetic energy (or momentum??) and dissipate it over time to reduce injury.

Other than the conservation of energy and Newton's first law, what other equations theories should i relate to these safety features and their function?

Any input or just a general push in the right direction would be greatly appreciated.
Thanks in advance, deman.
 
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  • #2
I am aware that the science in car crashes is all about reducing the stopping time, both of the car and occupant and that safety features need to take the occupants kinetic energy (or momentum??) and dissipate it over time to reduce injury.


I'm not sure about the "reducing the stopping time" part of this statement. What kills people in a crash is there is not enough stopping time. Let's say you jump from a building and hit the street. This would be an example of zero "stopping time". If you land on a fire department air matress instead, your "stopping time" would be longer. In the first case, you are subject to intense deceleration. In the second, a more gentle deceleration.

For cars, think crumple zones and air bags.
 
  • #3
Yes, my bad. I actually meant increase both stopping distance and stopping time. I've done some research and this is what i have so far, I don't know how much is right.

Seatbelts
- A seatbelts job is to act against Newtons 1st law (inertia) and prevent the occupant from hitting the steering column or windshield (in which the stopping time would be 0).

- Seatbelts that stretch upon collision offer a longer stopping distance, applying less force on the occupant.

relevant equations: V = d/t, p = mv, Work = force x distance

Airbags
- Airbags increase the time during which the occupants momentum decreases (stopping time)

- The large surface area of the airbag helps dissipate energy equally over the full surface area of body resulting in less injuries.

relevant equations: V= d/t, pascals principle.

Brakes
- Work with Newtons second law by decreasing acceleration and therefore decreasing the force behind the vehicle.

- Brakes turn kinetic energy into heat energy through the friction between the brake pads and wheel rotor and the friction between the tyres and road, thus decelerating the vehicle.

relevant equations: F = ma.

Still working on Crumple zones but i imagine they work in the same manner as airbags.

Please feel free to point out any incorrect statements and to add to any equations/theories. I'm sure I am missing something.
 
Last edited:
  • #4
I think you are doing great.

You may try to analyze most of the cases in terms of safe way of dissipating kinetic energy.
 
  • #5


Hi deman,

First of all, welcome to the world of physics! It's great that you're learning about the science behind car safety features. Let's dive into the topic a bit more.

As you mentioned, the main goal of car safety features is to reduce the stopping time and dissipate the kinetic energy of the car and its occupants over a longer period of time. This is because a sudden and abrupt stop, as in a car crash, can cause a lot of damage and injury due to the high amount of energy involved.

To understand this better, we can look at Newton's second law of motion, which states that the force applied to an object is equal to its mass multiplied by its acceleration (F=ma). In the case of a car crash, the force applied to the car and its occupants is the force of impact. The higher the force, the more damage and injury can occur.

This is where the safety features come in. Seatbelts, for example, are designed to stretch and absorb some of the force of impact, thereby reducing the force applied to the occupant's body. This is known as the impulse-momentum theorem, which states that the change in momentum of an object is equal to the impulse applied to it (Δp = FΔt). By increasing the stopping time (Δt), the force (F) is reduced, thus reducing the overall impact on the occupant's body.

Airbags also work in a similar way. They are designed to inflate quickly upon impact, increasing the stopping time and reducing the force applied to the occupant's body. This is also related to the equations of motion, specifically the equation for acceleration (a = Δv/Δt). By increasing the time (Δt), the acceleration (a) is reduced, resulting in a lower force of impact.

Crumple zones, which are designed to absorb and dissipate the kinetic energy of the car upon impact, also play a crucial role in car safety. This is related to the conservation of energy, which states that energy cannot be created or destroyed, only transferred or transformed. By absorbing and dissipating the kinetic energy of the car, the crumple zones reduce the force of impact and thus reduce the potential damage and injury.

Lastly, brakes also play a key role in car safety. The equation for kinetic energy (KE = 1/2mv^2) can be used to understand this. By applying
 

What is the purpose of car safety features?

The purpose of car safety features is to protect passengers and reduce the risk of injury or death in the event of a car accident. They are designed to absorb impact, distribute force, and minimize the effects of collisions.

How do car safety features work?

Car safety features work in various ways, depending on the type of feature. For example, airbags deploy upon impact to provide a cushion for passengers, seat belts keep passengers securely in their seats, and anti-lock braking systems prevent wheels from locking up during sudden braking. Other features, such as electronic stability control and blind spot detection, use sensors and computer systems to assist drivers in avoiding accidents.

What are some common car safety features?

Some common car safety features include airbags, seat belts, anti-lock braking systems, electronic stability control, blind spot detection, lane departure warning, and rearview cameras. Newer cars may also have advanced features such as automatic emergency braking, adaptive cruise control, and pedestrian detection systems.

How do car safety features improve over time?

As technology advances and more research is conducted on car safety, car safety features continue to improve over time. Manufacturers are constantly developing and implementing new features to enhance the safety of their vehicles. For example, newer cars may have more airbags and more advanced sensors and computer systems compared to older models.

Are car safety features effective?

Yes, car safety features have been proven to be effective in reducing the risk of injuries and fatalities in car accidents. According to the National Highway Traffic Safety Administration, seat belts alone saved over 14,000 lives in 2016. Additionally, studies have shown that newer safety features, such as automatic emergency braking, can reduce the number of rear-end collisions by up to 40%.

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