When the ball is in flight, the earth pulls on the ball downward (gravity), the ball pulls on the earth upward (gravity).
(the ball; is; in flight) (the earth; pulls; on the ball; downward; T:When the ball is in flight) (the ball; pulls; on the earth; T:upward)
the ball the earth the ball
is pulls pulls
in flight
on the ball downward T:When the ball is in flight
on the earth T:upward