Ok, here's an easy way of stopping the rotation of an object in a closed
system:

  Construct a cannon on the surface of the object so that it will shoot
in the direction of the tangent, towards the rotation direction. Shoot
a heavy-enough object fast enough so that the recoil of this shot will
stop the rotation of the main object. (If you are worried about possible
effects of having just one such cannon on the surface of the object then
just put another identical cannon at the opposite side of the object,
aimed towards the opposite direction, ie. still at the direction of
rotation at that side, and fire both cannons simulatenously.)

  The projectile is attached to a cable connected to the object at a
point where the pull caused by the object when it reaches the cable
length causes an even force on the center of mass of the object. (Such
a point must exist because there are two extremes: Attaching the cable
on the object at the point where the cannon is would effectively negate
the whole operation. However, attaching the cable on the opposite side
of the object would actually make it start rotating in the opposite
direction compared to the original one. A balance point must thus exist
somewhere in between.)

  When the projectile has thus been stopped, just pull it back to the
surface of the object. The rotation of the whole system will have stopped
without permanently ejecting any material.

  (Where did all the angular momentum go? Well, stopping the projectile(s)
will require energy. The majority of this energy will be dissipated as
heat from the cable.)

-- 
                                                          - Warp

Post a reply to this message