Rolling in a cone, normal force

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SUMMARY

The discussion centers on the calculation of the normal force exerted by a cone on an object rolling inside it. The user initially misunderstands the relationship between the normal force (N) and its vertical component, mistakenly using N/sinθ instead of the correct N*sinθ. The resolution involves recognizing that when decomposing forces, the perpendicular component cannot exceed the actual force magnitude. The correct approach involves treating the weight as the hypotenuse of a triangle to derive the appropriate expressions for the components of the forces involved.

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  • Knowledge of vector decomposition in physics.
  • Basic geometry related to triangles and angles.
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  • Explore problems involving normal forces in conical shapes.
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KEVmathematics
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I have a small problem with this question. In this problem, the cone exerts a normal force. This force, should be perpendicular to the inside surface of the cone. In equating the vertical forces, I need the vertical component of this normal force. I would draw this force perpendicular to the surface, and then using the angle θ, I would get a force of N/sinθ. But in the book, it says that it should be N*sinθ. What am I doing wrong here?
 

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Suddenly, I get it. Never mind! I can't find how to delete this thread.
 
You are decomposing the weight into its components which will be parallel and perpendicular to the inner surface of the cone. How can the perpendicular component have a magnitude greater than the actual force? Whenever you split a force at any angle, you get a value between 0 and the magnitude of the force depending upon the angle. Make the weight the hypotenuse of the triangle and see what expression you get.
 
Last edited:
KEVmathematics said:
Suddenly, I get it. Never mind! I can't find how to delete this thread.
As far as I'm aware, that is not possible. And why delete proof that you resolved your own doubt?
 

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