it is not a penalty if the person you hit is the ball carrier. but it is however a penalty if the hit a lineman or any other non ball carrier.
no it will be a 15-yard penalty
If you bang you knee right below the knee cap (patella), you will hit your shin bone (tibia). If you hit right on the knee it will be your patella.
No, unless either of your hands touch the ground, or your head/helmet.
No!
No, no penalty. Just watch out. It is a one shot penalty if you hit the bag or equipment with your ball.
hammer knee
Knee is used as both a noun and as a verb as in to touch someone with a knee or to hit someone with a knee.
Once you have taken the penalty and hit the new ball, you may not hit the old ball again. Play on with the penalty and the new ball.
your knee cap
If you fall and hit your head, a helmet will make it hurt less.
If you hit your head on something, the helmet will spread and soak up some of the energy of the hit, reducing your risk of head injury. If you don't hit your head, the helmet won't do anything. In extremely rare cases, the helmet will snag on something and yank on your head/neck.
The school girl had short red hair and freckles.When I was a school girl, our uniforms had to hit just below the knee.