No it is not legal to have any contact with the goalkeeper.
No, you can't.
A football with full air is heavier.
How much air in football
there is air in a football.
Air resistance is a contact force because you are in contact with the air in order to apply that force.
Contact Air was created in 1974.
A player is allowed to catch the football as long as..... the player that is on the line of scrimmage is not covered up by another player that is on the line of scrimmage as well. Usually though, everybody but the linemen go out for passes. If the ball is tipped in the air due to a defenders hand, then anybody is allowed to catch the ball
air is in the football
air!
to hold air
Yes, the football will appear "flat" as the air compresses in cold weather. Air expands as it warms, and so air in a football, tire, etc. will do the same.
Air India - football club - was created in 1952.