Centripetal force on a vehicle while cornering

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Discussion Overview

The discussion revolves around the concept of centripetal force as it applies to vehicles, particularly cars and bikes, while cornering. Participants explore the implications of Newton's third law in this context, examining the forces at play during a turn and the nature of friction involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants reference Newton's third law, questioning how a vehicle exerts an outward force while turning, which seems counterintuitive.
  • One participant suggests that centripetal force is provided by electromagnetic interactions between the vehicle and the Earth, implying a mutual force exerted by both entities.
  • Several participants emphasize the concept of equal and opposite friction forces acting on both the vehicle and the road, noting the complexity of these interactions.
  • A participant draws an analogy to a football player changing direction, suggesting that the force exerted by the shoe on the ground is similar to the interaction between tires and the road.
  • Another participant discusses the effects of steering and the resulting forces, mentioning that the Earth would counter-rotate in response to the vehicle's movement, albeit minimally due to its mass.
  • There is a repeated emphasis on the counterintuitive nature of the forces involved when a vehicle turns, with multiple participants expressing similar sentiments.

Areas of Agreement / Disagreement

Participants express a range of views on the nature of forces during cornering, with no clear consensus reached. The discussion remains unresolved regarding the specific mechanics and implications of these forces.

Contextual Notes

Participants highlight the complexity of the interactions involved, including the effects of mass, friction, and the mechanical properties of the materials in contact. There are mentions of dissipative effects and the limitations of applying Newtonian physics in this context.

Mohamad
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According to the Newton's third law "For every action, there is an equal and opposite reaction." When a car (or a bike) turns, How does the car (bike) exert force outward (in the opposite direction of centripetal friction force)?
 
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For a car to move in a circle there must be some centripetal force, which through friction on the road is provided by electromagnetic interactions of the matter making up the Earth with the matter making up the car. Neglecting retardation to stay within the approximations of Newtonian physics, the 3rd Law (i.e., spatial translation invariance) implies that the car exerts an opposite force of equal magnitude on the Earth.
 
Mohamad said:
How does a car (or a bike) exert force outward (in the opposite direction of centripetal friction force)?
Friction between two objects means two equal but opposite friction froces, each on one of the objects.
 
A.T. said:
Friction between two objects means two equal but opposite friction froces, each on one of the objects.
I mean, that is counter-intuitive that when you turn the steering wheel, car exerts an outward force (perpendicular to the car) on the road.
 
Mohamad said:
I mean, that is very counter-intuitive that when you turn the steering wheel, car exerts an outward force (perpendicular to the car) on the road.

Think of a football player that is avoiding a defender by making a quick change of direction. He digs in the side of his foot and pushes off in the opposite direction. The force of the shoe on ground compresses some dirt. The force of the ground on the shoe is what pushes him off. The interaction between the shoe and the ground is analogous to the tires and the street.
 
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Mohamad said:
I mean, that is counter-intuitive that when you turn the steering wheel, car exerts an outward force (perpendicular to the car) on the road.
When you run over a rug, and try to make a turn, the rug can slide outwards if not fixed.
 
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Mohamad said:
According to the Newton's third law "For every action, there is an equal and opposite reaction." When a car (or a bike) turns, How does the car (bike) exert force outward (in the opposite direction of centripetal friction force)?

You can consider the force (action) and the opposite only considering the whole system, car and earth. The two forces give zero sum for the whole system.

At steering Earth will counter rotate, (if perfectly rigid body), but i will not even try to measure how much.
In reality Earth will counter rotate for the force remaining at net of all dissipative effect ending in heat (deformation of tires, asphalt, road substrate, dow to geology deformation..) i think close to zero.
The main forcesarise from there mechanical effects, outside the car.

maybe a more clear situation is straight acceleration, a car star accelerating (big), the Earth accelerate (very little) in opposite direction, the two forces are equals and opposite, the difference is in the mass of the two objects of the system.
Centripetal acceleration from steering is the same.
 

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