How should you form football and physics?


For a long time, thanks to warm-up as a tournament, flight delays and long hours watching TV. This is a very important time for football calendar, along with playoffs as for college football and for the NFL.

But what impact do these impacts have? I do not remember football from the point of view, but I do not go through the hits. When I see this some epic solution, I can not help but think about physics.

There are great tools in order to analyze the football hitting physics. Indeed, we have everything. Individual players masses Yup – just get rid of the search and you can look it all up. Video Analytics Tools? Again, yes. Personally I really like tracker video analysis. There are only two things we need for complete analysis. I need a video footage, but it is trivial. Although some impacts are slowly moving, they are shown in real time. What about the remote scale? Wait! Where is the field in the yard We're all set.

Let's start with a collision. I only searched for "big football hits" and quickly found one that would work. In this case, I'm going to look at Clemson against the Syracuse game in 2017. The play has Clemson wide receiver Trevion Thompson (205 lbs) tackled by Parris Bennett (216 lbs) from Syracuse.

I like this collision for two reasons. First of all, the mediator is mostly in the area and not the side. This means that the camera takes the side view and they come out of the yard lines for easy measurement. Secondly, Bennet actually gives Thompson and tries to come back. It looks cool.

Now, one small problem. The camera zooms in and promised. This means that the change of origin will change in terms of camera and pixel-to-meter compression coefficients. Fortunately the tracker video analysis has an excellent method to make this camera move – calibration point pair. Basically, you set the scale of the video and then control the two points in the background. The application then chooses virtual coordination, so you can refer to the real location of the two players. This is the result of transformation.

Next, I just need to point out the location of both players in each frame. This is what I get.

Because this position-time plots, the line slope will give the player the speed. Here's what I get. I mean one meter in a second, because I'm not Barbara.

  • The initial speed Bennett = 6.05 m / s
  • Original Speed ​​Thompson = -1.33 m / sec
  • The final speed is Bennett and Thompson = 3.03 m / s

Great. But what can we do with these values? The answer is "more physics". Let's start with the principle of impulsion. It points out that the total strength of the object (or player) is equal to the change of impulses. But what is the momentum? This is a product of mass and speed (represented by p). In fact, I can write the impulse principle in terms of change, such as:

Yes, momentum and holy power are both vectors. In this case we mean only one dimension, so this is not really a big deal.

Here is another important physics idea: the forces interact between two relationships. When Bennet Thompson Welcomes, It Is Not Just One Way To Power. In fact, Thompson reaches Benet's equal and opposite force. This is not Thompson, it is the nature of the forces. If Bennett hit the brick wall, the wall will still push back the same power. During this interaction (also known as a hit), two players have equal and opposite forces, but they have the same time interval. Bennett can not push Thompson at different times that Thompson pushes Bennett. Since they have the opposite force, at the same time it means that they have different changes. Or better, before the start of the collision, the whole impulse is equal to the total impulse that occurred after the collision. This is the momentum conservation.

OK, let's write this as a one-dimensional equation in the direction of motion. I'm going to call on the direction that Thompson begins to move as a negative direction. This means that the impulse can be written:

I have a value at the original and ultimate speed as well as for the masses (convertible in kilograms). I checked it. According to the data, the initial impulse (I remember one of them negative) will be 469.5 kg ᐧ M and the final impulse will be 579.1 kg ᐧ m / sec. Yes, this is not the same but they are not far apart. Here are calculations (and more). You can change the numbers and click "play" for fun to entertain (and you need). Yes, Python is an awesome calculator.

So why is not immune conservation? It is not protected because there is another external force that is not registered. No, this is not a gravitational force. True, there is indeed a gravitational force that flows below, there is a powerful force from above. The lost force is sideways increases the power of the ground (frictional power) due to Bennett pushing forward because he collides with Thompson.

I can approach the contact time in about 0.2 seconds, then the external force must be 548 nutton (123 pounds barbos). Wait! This is a power system consisting of both players. If we look at Bennett, he must make a bigger force on land that will compensate Thompson to push him. I can say that Thompson's power to look at his change of impulse at the time interval. This gives the power of 2577 Newton's feet to come. Yes, this crazy is high, but its body weight is three times less. People can easily achieve those super-high forces in a short period of time (see, for example).

If you want something homework, here's something to try. Find another collision in which both players are at the time of disconnection. If both people are disabled, then there will be no progress. Momentum should be protected. See if the numbers work. Ე will be fun.


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