Can wide receivers get tackled without the ball?
Depends how you define the term “tackled” - a strict definition is you can only be tackled if you’re a ball carrier; otherwise you’re only an eligible receiver and there are strict limits on where you can legally make contact with one of those. In both the college and pro game, defensive backs are allowed to bump or jam receivers after the start of a play, providing it’s done within five yards of the line of scrimmage and before the pass is thrown. After that (i.e the receiver’s past that five yard zone), any contact is judged illegal and will draw a penalty flag unless it happens a fraction of a second before the pass arrive at the receiver and the DB covering him is making a play on the ball (i.e he’s looking back at the ball and trying to catch it himself or knock it down). Any contact made then would be ruled incidental and wouldn’t be flagged (as the DB is just as entitled to catch the ball as the wideout). But if the DB isn’t looking at the ball (i.e he hits or grabs the receiver to avoid giving up a long catch or even a TD), then that’s certainly illegal and will draw a pass interference penalty (spot foul, automatic first down at point of infraction unless in end zone, when ball is spotted at the one yard line). The other way a DB could get away with it would be timing his hit so that he makes contact with the receiver just as he catches the ball, knocking it loose for an incompletion or turnover. That again wouldn’t draw a flag.
Inelastic collision problem help please?
A 90kg fullback moving east with a speed of 5 m/s is tackled by a 95kg opponent running north at 3 m/s. if the collision is perfectly inelastic, calculate (a) the velocity of the players just after the tackle and (b) the kinetic energy lost as a result of the collision. Can you account for the missing energy? Momentum is conserved Since the players are moving perpendicular to each other before the collision: East component of the total momentum after the collision = 90 * 5 = 450 kg*m/s North component of the total momentum after the collision = 95 * 3 = 285 kg* m/s The magnitude of the of the total momentum after the collision is the length of the hypotenuse of the right triangle with north side = 285 kg* m/s; and East side = 450 kg*m/s Hypotenuse = (285^2 + 450^2)^0.5 = the magnitude of the of the total momentum after the collision = 532.7 kg* m/s Tangent of Angle North of East = East component ÷ North component Tangent of Angle North of East = 450 / 285 Angle North of East = Inverse tangent of 450 / 285 = 57.65° Since the collision is perfectly inelastic, the mass of the total momentum = 90 + 95 = 185 kg Velocity of the players just after the tackle = total momentum ÷ total mass Velocity of the players just after the tackle = 532.7 ÷ 185 = 2.88 m/s at angle of 57.65° North of East Kinetic energy of players just after the tackle = ½ * 185 * 2.88^2 Kinetic energy of players before the tackle = ½ * 90 * 5^2 + ½ * 95 * 3^2 Loss of KE = kinetic energy of players before the tackle – kinetic energy of players just after the tackle To account for the missing energy, you need to ask the 2 football players how they feel just after the tackle. During the tackle, collision, of the 95 kg tackle and the 90 kg fullback, a whole bunch of muscle was squished and twisted. This is similar the front bumper of my car and the back bumper of another car about a week ago. The energy that was kinetic energy was used to bend the metal bumpers. The missing kinetic energy of the 2 football players was used to twist and squish muscles, tear the shirt of the full back, and raise the temperature of the bodies a few degrees. East component of the total momentum after the collision = 90 * 5 = 450 kg*m/s North component of the total momentum after the collision = 95 * 3 = 285 kg* m/s
What happens when an NFL referee gets in the way of a play?
Nope, the play always counts unless there's a flag down.While officials do their best to get out of the way, it's up to the players to avoid them. Typically, the Umpire is in the most dangerous position behind the linebackers. However, everyone knows where he's supposed to be on the field, so it is a players responsibility to avoid being picked or interfered with by him, just as it's the role of the Umpire to avoid wandering outside of his usual territory and stumbling into the play.I was a minor league football official for a few years. The majority of our training boiled down to "position yourself to best observe the play safely." Officials in high level games have spent decades working on their positioning. Once again, if you think about how close the Umpire is to the thick of the action, it's surprising he doesn't get injured or in the way of the play more often!BTW, I'm not big fan of the recent decision by the NFL to reposition the Umpire in the offensive backfield for the majority of the game. I've always felt the simple solution to this is to acknowledge that this official should be given a helmet and pads to mitigate incidental contact.