Which Object Will Roll Farther: Solid Cylinder or Hoop on an Incline?

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A solid cylinder rolls down an incline faster than a hoop due to its lower rotational inertia, but the question arises about which will roll farther on a flat surface after reaching the bottom. The total energy of both shapes should be calculated to determine which has greater energy for rolling distance, as energy conservation plays a crucial role. The discussion highlights the importance of considering rolling resistance and the nuances of air resistance, questioning whether it refers to the same force or coefficient. The outcome may depend on these variables, as they influence the energy dynamics of both objects. Ultimately, understanding the energy transformations is key to predicting the rolling distances of the solid cylinder and hoop.
Keissterr
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Homework Statement


This is a question I have for a presentation on rotational motion: "A solid cylinder rolls down an incline faster than a hoop [or say an open cylinder], whether or not they have the same mass or diameter. The hoop has greater rotational inertia relative to its mass than a cylinder does." Now my question is when they reach the bottom of the incline to a flat surface, which one will roll the farthest? (if their masses are the same) Suppose the amount of friction and air resistance are the same for both.

Homework Equations

The Attempt at a Solution


I'm guessing that the hoop will since it has greater rotational inertia to keep it rolling, but another professor thinks it may be the solid cylinder.
 
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Keissterr said:
I'm guessing that the hoop will since it has greater rotational inertia to keep it rolling, but another professor thinks it may be the solid cylinder.

calculate the total energy of the hoop and the solid cylinder and see which is larger so one having the larger energy will traverse larger distance on the flat surface after completing the rolling down on the incline.
 
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drvrm said:
calculate the total energy of the hoop and the solid cylinder and see which is larger so one having the larger energy will traverse larger distance on the flat surface after completing the rolling down on the incline.
Better still, consider where that energy came from in the first place,
@Keissterr , you mentioned friction. I assume you meant rolling resistance.
With regard to drag (air resistance), it depends what you mean by being the same. Do you mean the same force, or the same coefficient but varying according to speed?
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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