Can't help about the glad question but I can answer how a stone gets you when it doesn't seem to make sense.

I was one lane over from a dump truck carrying (and slowly depositing some) stones and i watched time and time again as a stone would fall off the back.

As they fell they start at the same speed as the truck and upon contract with the ground forward inertia would slide the stone along the ground at 55 mph.

The stone would start to spin rather fast. Think of the RPM needed to go 55 when you have a radius less than a cm!

So it spins picking up more and more RPM, hopping each time it contacts the ground.

When the timing works out just right that a longer axis is about to hit the ground from the spin it'll hop 3-4' in the air.

They would typically bounce 4-6x before the big hop, typically bouncing less than 6 inches but about 10–20 % of them would do the big hop.

Saw maybe 20 stones hopping no more than a foot off the ground but 3-4 doing the big hop and it was right beside me one lane over was fascinating to watch.


–awr–

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)