Description using Newton's laws

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    Laws Newton's laws
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Discussion Overview

The discussion revolves around the application of Newton's laws of motion to a scenario involving a car making a left turn from uniform motion. Participants explore how these laws explain the behavior of objects inside the car and the forces at play during the turn.

Discussion Character

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

Main Points Raised

  • One participant describes how Newton's first law indicates that objects in motion tend to stay in motion, leading to objects inside the car appearing to move towards the outside of the turn.
  • Another participant points out that the car is not an inertial reference frame, suggesting that an additional force must be considered for objects inside the car due to its acceleration.
  • There is a discussion about the role of the road in providing the necessary frictional force for the car to turn, with one participant emphasizing that without this force, the car cannot make the turn.
  • Participants debate the relevance of Newton's third law, with some arguing it is not necessary to explain the turning motion, while others assert that it is always applicable when forces are exerted.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of Newton's third law in explaining the scenario, indicating a lack of consensus on its relevance to the turning motion. There is also some disagreement regarding the interpretation of the forces acting on the car and objects within it.

Contextual Notes

Some assumptions about the nature of the forces involved and the conditions of the road (e.g., friction) are not fully explored, which may affect the understanding of the scenario.

TheShapeOfTime
Let's use the scenerio of a car going from uniform motion, to a turn to the left. I'm trying to describe this in relation to Newton's laws in hopes to get a greater understanding. What I know is that objects in the car are affected by Newton's first law, which states (among other things) that objects in motion wish to stay in motion. Thus, the objects move towards the outside of the turn. As for the second law, what causes the unbalanced force? Does the third law come into play here?
 
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You forgot that the car itself isn't an inertial reference frame. This is an accelerating reference frame we're talking about. To compensate for the frame change, we have to add a force on every object inside the frame, pointing in the opposite direction to the movement of the reference frame.
If you judge from an outsider's point of view, the object is just moving in a straight line.

You don't need the third law to explain this.
 
TheShapeOfTime said:
What I know is that objects in the car are affected by Newton's first law, which states (among other things) that objects in motion wish to stay in motion. Thus, the objects move towards the outside of the turn.
Right. Unless a force is exerted on an object, it will keep moving in a straight line. For objects not firmly attached to the car, that's just what they do. (From inside the car it looks like they are being pulled towards the outside of the turn.)
As for the second law, what causes the unbalanced force?
What do you think? What's the only thing (except for air) in contact with the car?
 
Doc Al said:
What do you think? What's the only thing (except for air) in contact with the car?

The road. :)

From what I understand, the third law is applies only when a force is applied to an object. In this example, the car pushes down on the road, and the road pushes back with equal force. But, the third law has nothing to do with the turning (unbalanced forces).
 
Right. If not for the road exerting a sideways force on the car, the car could not turn. For an unbanked road, that force is a friction force. Take away the friction--try making a sharp turn on a patch of oil or a sheet of ice--and you can't make the turn.

Of course, whenever a force is exerted, Newton's 3rd law comes into play. If the road pushes the car, the car pushes the road.
 

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