Assertion: ballpoint pen's metal ball | /r/AtLocation | constant contact
Facets:
value: with the ink in the cartridge
type: OTHER
value: at the tip of the pen
type: LOCATION
value: by the force of gravity
type: CAUSE
Source sentences:
text: At the tip of the pen, a metal ball in a socket remains in constant contact with the ink in the cartridge by the force of gravity.