Why we wear seat belts in terms of momentum?

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Discussion Overview

The discussion revolves around the reasons for wearing seat belts, specifically in relation to the concept of momentum. Participants explore the effects of seat belts during collisions and compare them to other scenarios involving different materials and conditions. The conversation also briefly touches on the role of sports shoes in running, linking it to momentum and energy storage.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant explains that without a seat belt, a person would continue moving forward at the car's velocity during a collision, potentially resulting in serious injury.
  • Another participant contrasts the use of a seat belt with an inflexible rod, suggesting that the latter would cause severe injury due to a rapid deceleration force.
  • It is proposed that seat belts allow for a longer deceleration time, thereby reducing the force experienced by the occupant during a collision.
  • A participant shifts the discussion to running, questioning how wearing trainers affects momentum and speed.
  • Another participant suggests that trainers might reduce the time taken to run a distance, potentially increasing the force exerted while running.
  • A participant from Norway seeks clarification on the term "trainer," leading to a humorous exchange about terminology differences.
  • One participant explains that sports shoes function like springs, storing kinetic energy during foot strikes and aiding in upward movement, which could enhance running efficiency.

Areas of Agreement / Disagreement

Participants generally agree on the benefits of wearing seat belts in terms of momentum and deceleration during collisions. However, the discussion about trainers and their effects on running remains less clear, with varying interpretations and no consensus reached.

Contextual Notes

The discussion includes assumptions about the mechanics of collisions and running, but these are not fully explored or resolved. The terminology used may also lead to misunderstandings, as seen in the exchange about "trainers."

Gughanath
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can someone please explain why we wear seatbelts in terms of momentum?
 
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Basically, you have two other options:
1) No seat belt.
When the car suffers a collision, you still have the velocity the car had.
Hence, you'd fly forwards through your front window..
Would you like that?
2)Seat belt/rod fastened to the car, but made of iron (or some other inflexible material).
In this case, you are forced to decelerate to zero as fast as the car does.
The rod would slice you through (a BIG force acting on you).
Not nice, IMO.


The seat belt allows you some longer time than in 2) to decelerate to zero, hence
the force acting on you will not be that great.
 
oh ok..i understand it now...
but how does wearing trainer in a run help run better in terms of momentum??
 
does it reduce the time taken to get from one point to another hence, increasing the force with which we run??
 
Since I'm Norwegian, there's quite a few English words I don't know so well..
Is "trainer" a tight-fightting suit? (or "condom suit" as we call it in Norway..:wink:)
 
hahahaha...lol...em...trainers are sports shoes...shoes that we wear when we run in a track or play inside a gym
 
Oh dear..:redface:
 
sorry...have i confused you??
 
As for the sport shoe, it works a bit like a spring; when your foot compresses it, some of the kinetic energy gets stored in the shoe, rather disappearing from you as when your foot strikes the ground.
In the upwards movement that stored energy aids you; you don't have to exercise that much force yourself to run at a given velocity as what you'de had to do if you were running bare-footed.
 

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