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Rhodes-Williams crater experiment - Silent film

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Published on Apr 27, 2011

My father, Roy Williams Jr along with his mentor Dr. William Rhodes shot this footage circa 1956 while Mr. Williams was working on a degree. I have no written documentation of the experiment, my father would briefly discuss it when he was showing it with other home movies when I was very young.
A base of dry cement powder, such as Portland Cement straight out of the bag, un-compacted, perhaps four inches thick, was used as the target. A heated ball bearing was used to form a spherical wax mold. Two wax rods were pushed against the hot ball creating the two hemispheres of the mold. The two separate hemispheres were gently pushed together while scooping dry cement powder into an un-compacted ball. By gently pulling the wax mold apart against a flat horizontal surface one could produce a nice uncompacted spheroid of powder. Such a ball is placed on a fall away platform some five feet above the target. The platform is suddenly removed, allowing the ball to fall by gravity onto the target.
The idea being that the parameters for the crater experiment, i.e., low density and same composition, low impact velocity due to low amount of acceleration time, were chosen to demonstrate similar, scalable, effects with regard to some of the craters we see on the moon.
The slow motion sequence was achieved by filming at 5000 frames per second and is very mesmerizing to watch on a large movie screen with ejecta continuing to fall for many seconds.
Of note is the somewhat ragged appearance of the main crater as opposed to the more circular seconday crater, along with the lines or rays of ejecta left over. No central peak is much evident.

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