Use Archimede's Spiral For Accelerate An Object.

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lba
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Hi,

Is it possible to help to accelerate an object with an Archimede Spiral ? We can apply a force F perpendiculary to the spiral, like this if we want to turn the spiral in its center we don't need energy. If we want to accelerate an object near the spiral, we apply a force F to the spiral, the spiral apply the same force in the contrary direction. The object accelerate. The spiral can turn without energy if the force F is perpendiculary to the surface (it's possible with an Archimede Spiral). Like the object accelerate, if we want always a contact between the spiral and the object, we need to accelerate the spiral, but this don't require more energy. In this case what is the energy need for accelerate the object ? It is the same without spiral ? Why ?
 

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The spiral is not a circle, so you can't have F perpendicular to it in this arrangement. So there will be some work of F, and energy will be consumed.
 
  • #3
lba
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You're right but if I use 4 centers like the figure show, it's not possible to turn the spiral without energy ? It's an approximation and a little energy is needed but less I think.
 

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You're right but if I use 4 centers like the figure show, it's not possible to turn the spiral without energy ? It's an approximation and a little energy is needed but less I think.
If the object to move is on a frictionless surface, then, theoretically, you need an infinitely small energy and infinite time to move the object to any distance, with or without the spiral. If, however, there is friction, then the force of friction will do work that is proportional to the mass of the object and the distance to move, and you cannot spend less energy than that, again, with or without the spiral.

All in all, the spiral gives you nothing in terms of energy.
 

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