🚀 go-pugleaf

This question has been puzzling me for awhile, but it should not
cause much trouble to you guys. (I hope.) (My scientific English
is not as good as it should be, so pardon any errors...)

Consider a staff, one meter long. Now, given the speed v it 'shrinks'
to half a meter. We then have a wall, and an easily controllable
hatch placed .75 meters from the wall. The staff passes through the 
hatch, and we close the hatch behind it (BEFORE it hits the wall!)
The staff hits the wall, without being deformed (somewhat unrealistic!),
and since its speed now changes to 0 it is now fully 1 meters long.
What the **** happens????

Anders, who likes to torture himself with questions he can't answer.