Can you tackle a runner by tripping him with your feet?

Answer 1

You can't tackle a player that doesn't have the ball in his possession. You can block any player you want -- you can even knock someone over with a pancake block -- but grabbing onto a player who doesn't have the ball and taking him to the ground would constitute holding.

Answer 2

No. If the defensive back hits a receiver before the ball is thrown it is Pass Interference (if the ball was already in the air) or Defensive Holding (if the ball hasn't been thrown yet). That said, the defensive back has as much right to the ball as the receiver, so if he is making a play on the ball the contact may be legal.

Answer 3

Provided they have the ball, you can tackle them wherever you like.

Answer 4

No it will be a tripping penelty

Answer 5

YES HE can