How do Dynamics/Kinetics relate to Football?
Dynamics/Kinetics, in general, is the branch of mechanics concerned with the study of forces and their effect on motion. With football being a sport of hitting and smashing, there is no better place to test and see Newton's laws, than on the football field. Concepts behind Newton's laws can be spotted everywhere, and are used to calculate the physics behind some of football's biggest events, such as a linebacker sacking a quarterback, a runningback plowing over a defensive back, and even a kicker swinging his leg, going for the game winning field goal. Since contact is inevitable in every play on the football field, Kinetics can be argued to be the biggest physics concept when it comes to football.
Exploring Dynamics/Kinetics in Football
To explore Kinetics in football, we have our guest star "Sayf Al-Omaishi" here to go through some more testing. In this section we will test the force Sayf can generate running over a defender, compared to some of the hardest strongest runners in the NFL. In addition to that comparison, we will show the physics behind how every football game begins, with an NFL kicker, kicking off the game.
The Truck
Brandon Jacobs
Brandon Jacobs is by far the hardest runner in the NFL today. His 6"4, 264 pound build make him a defenders worst nightmare, at his running back position. Although he plays running back, his size compares to some of the NFL's largest linebackers, and he outweighs the average running back today by about 50 pounds! For a big man, this Louisiana native can also run. He clocked in a 4.56s on the 40 yard dash, which is terrifying and unheard of for his massive size. With his natural size and speed, this running back can bring defenders in his way to tears. Let's see how guest star Sayf Al-Omaishi's running force compares to Brandon Jacobs... If it can even compare in the first place...
Sayf Al-Omaishi
Sayf's build does not quite match up to Brandon Jacobs', the way we would like it too. Sayf has a quite average, 6"0, 185 pound structure. At our testing grounds, for our Kinematics portion, we measured Sayf's acceleration, and since we have his mass, we could find the force Sayf can produce running over a defender (If he can even run over one).
Brandon Jacobs, in the video above, produced 2480 pounds of force when running over the stationary defender. This can be translated into 11 032 N of force. Let's see how the force of Sayf's impact can compare...
Brandon Jacobs, in the video above, produced 2480 pounds of force when running over the stationary defender. This can be translated into 11 032 N of force. Let's see how the force of Sayf's impact can compare...
Impact Force and Reaction Force
Fg = M x ag
Fg = (85kg) x (9.8m/s²)
Fg = 833N
Fn = Fg
Fn = 833N
Sayf's Mass = 85g
Sayf's Acceleration (Found in Kinematics) = 2.61m/s²
Sayf's Applied Force according to his mass and acceleration, and according to Newton's 2nd Law.
Fa = ma
Fa = (85kg)(2.61m/s²)
Fa = 223N
Also, according to Newton's 3rd Law, each force has an equal and opposite reaction force... So if Sayf makes contact with 223N of force, reaction force will be equal in the opposite direction. (Force Applied=Reaction Force=223N)
Fg = (85kg) x (9.8m/s²)
Fg = 833N
Fn = Fg
Fn = 833N
Sayf's Mass = 85g
Sayf's Acceleration (Found in Kinematics) = 2.61m/s²
Sayf's Applied Force according to his mass and acceleration, and according to Newton's 2nd Law.
Fa = ma
Fa = (85kg)(2.61m/s²)
Fa = 223N
Also, according to Newton's 3rd Law, each force has an equal and opposite reaction force... So if Sayf makes contact with 223N of force, reaction force will be equal in the opposite direction. (Force Applied=Reaction Force=223N)
Verdict
After looking at the numbers, this one is probably the ugliest. According to Newton's 2nd Law of motion, force equals the mass, multiplied by the acceleration of which it's moving. In the Kinematics section, we found Sayf to have an acceleration of 2.61m/s², and using his 85kg mass, we found that he produces a weak force of 223N. Comparing this to Brandon Jacobs' smashing force in the video above of over 11 000 N, would not even be fair... Sayf better hit the gym if he thinks he's going anywhere in football.
The Kickoff
Every football game begins with a kickoff. Although kicker's are known to be least powerful, and weakest on the team, they actually can generate a lot of force that is not noticed and respected enough by the majority of football fans.
According to Newton's 1st law, of Inertia, an object at rest or moving with constant velocity will stay at rest or moving with constant velocity, unless enacted upon by an unbalanced force. This law is captured in the kickoff in a couple ways...
To begin the kickoff, the ball is at rest in the middle of the field and remains at rest until it is struck by the unbalanced force from the kickers kick. The kick is a huge unbalance in power, as the average force of an NFL kicker's foot during a kick is about 450 pounds of force (2002N), even causing the ball to deform upon contact.
Once the ball is kicked and is up in the air, it would like to continue to move at it's velocity, but is enacted upon by the unbalanced forces of air resistance and gravity, bringing the ball down and stopping it from moving any further.
According to Newton's 1st law, of Inertia, an object at rest or moving with constant velocity will stay at rest or moving with constant velocity, unless enacted upon by an unbalanced force. This law is captured in the kickoff in a couple ways...
To begin the kickoff, the ball is at rest in the middle of the field and remains at rest until it is struck by the unbalanced force from the kickers kick. The kick is a huge unbalance in power, as the average force of an NFL kicker's foot during a kick is about 450 pounds of force (2002N), even causing the ball to deform upon contact.
Once the ball is kicked and is up in the air, it would like to continue to move at it's velocity, but is enacted upon by the unbalanced forces of air resistance and gravity, bringing the ball down and stopping it from moving any further.
Kicking Forces
Fa = 2002N
Fg = M x ag
Fg = (0.4kg) x (9.8m/s²)
Fg = 3.92N
Fn = Fg
Fn = 3.92N
Reaction Force = Fa
Reaction Force = 2002N
Next time you watch football, appreciate the fact that kicker's can generate more force than you think! These players may be small compared to the rest, but they can generate some BIG force, and make a BIG impact on a football game...they can be the difference between winning or losing.
Fg = M x ag
Fg = (0.4kg) x (9.8m/s²)
Fg = 3.92N
Fn = Fg
Fn = 3.92N
Reaction Force = Fa
Reaction Force = 2002N
Next time you watch football, appreciate the fact that kicker's can generate more force than you think! These players may be small compared to the rest, but they can generate some BIG force, and make a BIG impact on a football game...they can be the difference between winning or losing.