How to prove a car must turn in a curve?

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    Car Curve
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Discussion Overview

The discussion revolves around the mechanics of a car turning in a curve, focusing on the relationship between the angles of the front and back wheels, the velocities of the wheels, and the implications of these factors on the car's motion. Participants explore theoretical and mathematical aspects of vehicle dynamics, including concepts like slip angles and the effects of wheel orientation.

Discussion Character

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

Main Points Raised

  • One participant notes that if the steering wheel is held at an angle, the front and back wheels must also be oriented accordingly, raising questions about how this affects motion.
  • Another participant suggests that the outer wheel may need to move faster than the inner wheel during a turn, but this raises concerns about maintaining the required wheel orientation.
  • Some participants discuss the concept of slip angles, indicating that the tires may not move in the same direction as their plane's normal due to deformation.
  • There is a suggestion that a solid axle connecting the wheels could hinder turning, as it would cause both outer and inner wheels to rotate at the same angular velocity.
  • One participant questions whether a car can still turn if the front wheels are fixed at an angle, prompting further exploration of the dynamics involved.
  • Another participant introduces the idea of the back wheels having different velocities, which could lead to a distortion in the distance between them during a turn.
  • There is a discussion about the implications of rigid tires and ideal contact points with the ground, questioning how this affects turning dynamics.
  • One participant expresses confusion about the relationship between tire velocity and the plane's normal, seeking clarification on these concepts.
  • Another participant emphasizes that the dynamics of turning involve more than just static friction, especially at non-zero speeds.

Areas of Agreement / Disagreement

Participants express various viewpoints and raise questions without reaching a consensus. There are multiple competing ideas about the mechanics of turning, the role of slip angles, and the implications of different wheel orientations.

Contextual Notes

Participants acknowledge limitations in their models and assumptions, particularly regarding the effects of tire deformation and the simplifications made in their discussions. The mathematical implications of wheel velocities and distances are also noted as areas requiring further exploration.

  • #31
The cars inertia will try to make it go in a straight line (a tangent to the curve). The front wheels point in a different direction so they provide a sideways force on the front of the car.

In effect inertia is trying to drag the froont wheels sideways and it's friction that provides the sideways force making the car turn. On ice you go straight on!

The same applies to an un powered soap box cart so makes no difference if the car is front or rear wheel drive.
 
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  • #32
hihiip201 said:
And are these "inward" forces reaction forces normal to the planes of the front wheels caused by the "forward" forces on front wheels by the back wheels?
That would imply it would only go around a bend if it were driven! If the wheels are not being braked, then there are no tangential forces on any of the wheels. Have you looked at all diagrams, read the google hits and tried to understand what they are trying to tell you? I have a feeling that you are hanging on to some idea that is hindering you from actually getting this. Try stepping back and starting again with this problem.
 
  • #33
sophiecentaur said:
That would imply it would only go around a bend if it were driven! If the wheels are not being braked, then there are no tangential forces on any of the wheels. Have you looked at all diagrams, read the google hits and tried to understand what they are trying to tell you? I have a feeling that you are hanging on to some idea that is hindering you from actually getting this. Try stepping back and starting again with this problem.
No I haven't yet, and I am going to just discard al preassumptions I have at this moment and read them...guess that's my best bet.I thought I knew, but I don't, not one bit, my arrogance has cost me 2 days of mental torment. And it is time I liberate myself , I will not ask anymore questions until I have squeeze every last bit of all the resources made available to me by you all good folks.
 
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