Is friction the main factor in determining braking distance?

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    Braking Friction
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Discussion Overview

The discussion revolves around the role of friction in determining the braking distance of a car under various road conditions, particularly contrasting icy or wet surfaces with those that are rocky or sandy. Participants explore the relationship between friction and braking distance, raising questions about the underlying physics concepts involved.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants assert that braking distance is greater on icy or wet roads due to lower friction, while others challenge this claim, suggesting that more friction would lead to shorter braking distances.
  • There is mention of a potential confusion between sliding friction and rolling resistance, indicating a need for clarification on these concepts.
  • A participant expresses uncertainty about the physics involved, asking for an explanation of the distinction between sliding friction and rolling resistance.
  • Another participant emphasizes that driving rules vary significantly with different road surfaces, implying that this affects braking behavior.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the relationship between friction and braking distance, with multiple competing views remaining on the topic.

Contextual Notes

There are unresolved assumptions regarding the definitions of friction types and their effects on braking distance, as well as the influence of different road conditions on driving behavior.

eddywalrus
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I was taught that in conditions where there is less friction, such as on icy or wet roads, the braking distance of a car, is less than if the car was traveling in conditions with more friction, such as when the road is rocky or sandy.

Although it makes sense intuitively, I recalled that friction opposes motion and not acceleration. So, for example, when a car travels to the right, and the driver applies the brakes, the car will still travel to the right, but just decelerate until it stops completely. Since friction opposes movement, and the car is still moving to the right when braking, then the direction of the friction force is to the left -- so shouldn't a larger friction force decrease the braking distance?

Thanks for your help!
 
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eddywalrus said:
I was taught that in conditions where there is less friction, such as on icy or wet roads, the braking distance of a car, is less than if the car was traveling in conditions with more friction, such as when the road is rocky or sandy.
There could be some confusion about sliding friction vs. rolling resistance here.
 
A.T. said:
There could be some confusion about sliding friction vs. rolling resistance here.

I'm not very knowledgeable when it comes to physics -- could you explain the distinction between the two for me? Thanks.
 
eddywalrus said:
I was taught that in conditions where there is less friction, such as on icy or wet roads, the braking distance of a car, is less than if the car was traveling in conditions with more friction, such as when the road is rocky or sandy.

Although it makes sense intuitively, I recalled that friction opposes motion and not acceleration. So, for example, when a car travels to the right, and the driver applies the brakes, the car will still travel to the right, but just decelerate until it stops completely. Since friction opposes movement, and the car is still moving to the right when braking, then the direction of the friction force is to the left -- so shouldn't a larger friction force decrease the braking distance?

Thanks for your help!

I don't know if you really meant this but the braking distance in ice is Greater than with more friction.
 
eddywalrus said:
I was taught that in conditions where there is less friction, such as on icy or wet roads, the braking distance of a car, is less than if the car was traveling in conditions with more friction, such as when the road is rocky or sandy.

This is most certainly wrong, or wrongly stated.

And the rules for driving vary with the type of road surface; you drive quite differently on gravel than you would on pavement.
 

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