kashiark
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I was thinking about it, and the only thing I could come up with is that it reduces friction with the surface the object is sitting on and perhaps it distributes weight evenly?
kashiark said:I was thinking about it, and the only thing I could come up with is that it reduces friction with the surface the object is sitting on...
atyy said:But does rolling friction come into play in ideal rolling without slipping - in such a case the point of contact is always stationary?
atyy said:But does rolling friction come into play in ideal rolling without slipping - in such a case the point of contact is always stationary?
kashiark said:Why is rolling friction less? It seems like common sense that it is, but why is it?
The question was why rolling friction is less than sliding friction. The area of contact of a rolling wheel is the same, as if the wheel slides. It is not the size of the contact area, but it's movement relative to the ground: In the rolling case the area of contact has no horizontal speed.Pengwuino said:The area of contact at all times is extremely small for a very spherical object
Pengwuino said:The area of contact at all times is extremely small for a very spherical object
negitron said:You can immediately falsify this statement by asking yourself why brakes work, since the area of contact with the ground doesn't change, the wheels just stop turning.
negitron said:Rolling friction occurs even when the wheel doesn't slip. Friction, as a general case, occurs when electrostatic forces act between the surface atoms of one body moving over the surface atoms of another. Sliding is not the only case in which this occurs. For a wheel, there is always some portion of it in contact with the surface over which it rolls, and as it turns, atoms on the wheel's leading surface are continually being mashed down onto the surface of travel where electrostatic forces weakly bind them then are pulled apart again at the trailing surface--the energy required to pull those weak bonds apart is what we call friction.
kashiark said:I see what negitron is trying to say. If the wheels aren't turning, the friction increases regardless of the small contact area of the wheel touching the ground.
kashiark said:However, could changing the atoms which are reacting with the ground decrease friction? Or am I just wrong?
negitron said:Rolling friction occurs even when the wheel doesn't slip. Friction, as a general case, occurs when electrostatic forces act between the surface atoms of one body moving over the surface atoms of another. Sliding is not the only case in which this occurs. For a wheel, there is always some portion of it in contact with the surface over which it rolls, and as it turns, atoms on the wheel's leading surface are continually being mashed down onto the surface of travel where electrostatic forces weakly bind them then are pulled apart again at the trailing surface--the energy required to pull those weak bonds apart is what we call friction.