(Henry Spencer) writes:

In article ,
Parallax wrote:
I recently read somewhere a story about one of the first underground
nuclear tests called Bernallilo in which the vertical shaft was capped
with a massive steel plug. After the shot which was intentionally
vented to the atmosphere, that the steel cap wasn't found.
Calculations indicated that its velocity far exceeded earth escape.
Apocryphal or plausible? A search on underground nuclear testing
reveals nothing?

Half-apocryphal. According to people who were there, the shaft (a steel
tube) was capped with a welded-on steel plate -- not terribly massive --
as an "oh, what the hell" afterthought. A quick back-of-the-envelope
calculation suggested that its *initial* velocity might exceed escape
velocity. This was not verified in detail, nor was any attempt made to
determine whether the plate would survive passage through the atmosphere.

And note that "escape velocity" assumes that the only force slowing you
down is gravity; this is why Henry specified the calculation was for its
initial velocity, and part of the reason you need to know what happened
to the plate while it was in the atmosphe it would have been slowed
by friction (it would have been heated by friction too, which is the
other interesting part of its trip inside the atmosphere; its survival
is not at all a sure thing).