Throwing a Football

Throwing a football When the football travels through the air for a long pass it always follows a curved path because the force of gravity influences the movement of the ball in the vertical direction. As the ball travels up, gravity slows it down until it stops briefly at its peak height; the ball then comes down, and gravity accelerates it until it hits the ground. Projectile motion is the path of any object that is launched or thrown and has an arched course (howstuffworks) For the football to travel the most accurate and furthest distance, the ball must have the tightest spiral it can develop. "This will influence how the ball slows down in flight, because the ball is affected by air drag (howstuffworks)." A spiraling throw will have less air drag, will not slow down as much and will be able to stay in the air longer and go farther than a wobble throw. The velocity of the ball and the angle of the throw are the major factors that determine the path of the ball. Vectors are also involved in throwing a football because a vector is the direction in which you are throwing. Also when throwing on the running. For example the quarterback rolls out at a speed of 5m/s and after he twist his body to throw down field the vector is now at an angle of 75 degrees, so the quarterback must understand the speed he is running at in order to make an accurate throw (physics.unl.edu).
Ø The football has a more streamlined design and consequently has less drag, allowing the ball to move more easily through the air.
Ø Launch speed
Ø Launch angle
Ø Air density and wind
Ø Spin of football
Ø The faster it rotates the more velocity it has, the farther it goesd
Hitting and tackling the running back
Newton's third law of motion says if two objects interact, they exert opposite and equal forces on each other. So when players collide, the force of the impact is distributed equally between them. "The foam and plastic padding that players use to arm themselves against injury may seem insignificant, but Bloomfield explains, even slight padding means energy must pass through more material before reaching the body. The resulting decrease in speed makes a big difference (abcnews)." Four important principles determine how successful a player is stopping the runner: impulse, conservation of momentum, collision, and rotational motion. Impulse is the product of the applied force and the time over which that force is applied. Because impulse is a product like momentum, the same impulse can be applied if one varies either the force of impact or the time of contact. In any tackle in which there is no force other than that created by the collision itself, the total momentum of those involved must be the same before and after the collision also known as the conservation of momentum. The two types of collisions or tackles are elastic and inelastic collisions. Elastic meaning the two players hit but do not remain together after contact and inelastic indicating that the two players stay attached after the contact. When tackling you are always taught to tackle low because the further you tackle away from the runners center of mass the less force is needed (howstuffworks).

Ø The momentum of a player is M x V. It takes a force to change his momentum
Ø Momentum changes when speed and direction change
Ø Forces exerted by the ground are important for good footing
Ø Leverage is important; if the force has a larger lever arm the opponent can be spun around.
Ø Example: The energy dispersed when two 280lb. Players collide at 15mph (5.0 – 40yd) has the equivalence to the energy of a 10lb. Watermelon dropped from 420ft.
Ø Player with most momentum goes in the same direction
Ø Lower you get as a lineman makes the opponent attack the center of mass.