Force is the result of energy exerted by a player which provides movement of the ball. The term force is used only in connection with the goal line and in only one direction, i.e., from the field of play into the end zone. Initial force results from a carry, fumble, kick, pass or snap. After a fumble, kick or backward pass has been grounded, a new force may result from a bat an illegal kick or a muff.
Tag: grounded
Rule 9, Section 7, Article 2
No player shall bat a loose ball other than a pass or fumble in flight, or a low scrimmage kick in flight which he is attempting to block in or behind the expanded neutral zone.
EXCEPTION: A K player may bat toward his own goal line a grounded scrimmage kick which is beyond the neutral zone and may also bat toward his own goal line a scrimmage kick in flight beyond the neutral zone, if no R player is in position to catch the ball.
The Zebra Files 