> Hello Jon,
> You wrote, 'How does a sled running on bedrock
> reduce the amount of effort required to move the
> Is the coefficient of friction of the underside of
> a wooden sled less than the underside of a
> In your opinion, would the Ancient Egyptians (or
> whoever) have needed to know about such things as
> 'coefficient of friction' in order to move and
> raise large blocks of stone such as those seen in
> these pits?
> Robin (MJT)
No but had they tried, they would have soon realised the principle empirically.
In exactly the same way as you do without any knowledge of "coefficient of friction" when you apply the brakes on your bicycle.
What happens when you sandwich a piece of wood (sled) between two hard rocks and apply downward pressure (weight)?
How does a "Brake" i.e. the stopping variety work?
Rollers would reduce the moving effort required, To place rollers under 15 ton block, raise one end (about 5 tons required) place roller. Raise opposite end (about 5 tons again) place second roller.
Dig two channels under the block, place rollers. Remove the remainder of the soil from under block, block now on rollers.
I prefer the second method because raising five tons (two average sized cars) with manpower and wooden levers would be an enormous undertaking.
Although the second method would be limited by the wooden rollers ability to withstand crushing under load.
Doable provided there is a reasonably level surface.
Rollers, unlike wheels will be brought to a grinding halt with even the slightest bump or obstruction in the road.
A sled does not reduce friction, even a sled with say two runners. The contact area is reduced, but the contact pressure is increased by the same amount. (you don't get something for nothing in this universe), At best a sled will provide a smooth running surface, Our blocks already have a smooth running surface. An integral sled.
There's a good reason why most stone circles and neolithic structures are comprised of blocks max. of around 15 tons.
I've no idea how anything larger than 20 tons could have been moved.
The best option is a wheel which is an infinite number of levers arranged around a common fulcrum, very clever.
Edited 1 time(s). Last edit at 14-Sep-16 20:09 by Jon Ellison.