From: bill.sloman@ieee.org   
      
   On 29/11/2025 3:14 am, Liz Tuddenham wrote:   
   > Edward Rawde  wrote:   
   >   
   >> "Liz Tuddenham"  wrote in message   
   >> news:1rmgdu2.kq9ug246pz0gN%liz@poppyrecords.invalid.invalid... > Edward   
   >> Rawde  wrote:   
   >>>   
   >>> [...]   
   >>>> What volume of material remains after a six inch long hole, centred on a   
   >>>> diameter, is drilled through a sphere?   
   >>>   
   >>> If the hole diameter can be regarded as small compared with the sphere   
   >>> diameter, the curvature at the ends can be neglected .  The calculation   
   >>> method will depend on the relative dimensions and the degree of accuracy   
   >>> required, so that should sort out the engineers from the theoretical   
   >>> mathematicians.   
   >>>   
   >>> It is also possible to get a negative answer if the hole is bigger than   
   >>> the sphere - which should sort out the accountants.   
   >>   
   >> If the sphere is as big as the earth then you'll find plenty of people who   
   >> don't get how you could theoretically drill a six inch long hole through   
   >> it and  still be left with the same volume as for any other sphere bigger   
   >> than six inches in diameter.   
   >   
   > You just keep the material you drilled out.   
      
   Neat trick.The solid surface of the earth, or outer crust, is drillable but   
      
   https://en.wikipedia.org/wiki/Internal_structure_of_Earth   
      
   the highly viscous asthenosphere beneath it probably isn't, the liquid   
   outer core certainly isn't and the solid inner core is probably   
   inaccessible to any kind of drill.   
      
   --   
   Bill Sloman, Sydney   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)