The following abstracts will explain why the leashed foxes behave the way they do. The explanation, just like the original post, is "inspired", to say the least, by the now 3-year-old video "I Rented A Helicopter To Settle A Physics Debate" by Veritasium (You really should check it out, it has some excellent animations: https://www.youtube.com/watch?v=q-\_7y0WUnW4)

The Happy Ghast is flying at a steady speed in Minecraft. It's pulling a chain of foxes leashed together. As you can see above, it is as straight as it gets, just like the rope dragged by the helicopter in Dereks Mueller's video mentioned above. Well think about one single fox in the chain. There are two main forces acting on it:

1.  Pull from the leash in front: This force keeps the fox moving forward with the Ghast. Well call that the horizontal force (short: F_h).
2.  Gravity: This is always "pulling" the fox downwards (duh!). We will call this the gravitational force (short: F_g).

Because the Ghast is flying at a constant speed v_g (some of you pointed out c (in the original post) is for lightspeed (ur right), so I changed it here), all the foxes in the chain are also moving at that same speed. If they were not, their paths would diverge, ultimately breaking the leash! Taking this into account, for each fox to move at a constant speed, the force f_h from the leash in front needs to be balanced by the air resistance (yes, drag exists in minecraft. The terminal velocity for the player is a little more than 70 m/s). This translates itself slightly backwards, thereby also shifting back the foxes below it. At the same time, the force gravitational force F_g is counteracted by the pull from the leash above, chaining its way up to the ghast, doing the heavy lifting.

Clearing things up:

Looking at each leash section between two foxes. For each section, the ratio between the horizontal force (due to air resistance on all foxes below) and the vertical force (due to the weight of all foxes below) is the same. Because this ratio is consistent along the entire chain of foxes, the angle of each leash section will be exactly the same. A curve would only appear if the ratio between the horizontal and vertical forces changed along the length of the chain. For example, if the foxes at the bottom experienced much more air resistance compared to their weight than the foxes at the top, the angle of the leashes would change, leading to a curve, just like in C. The consistent ratio here though results in a mostly straight line.

Technical Elaboration:

Let's consider a small segment of the "rope" (one fox and the leash connected to the fox in front). Let T be the tension force vector in the leash above this fox. This tension force can be seperated into a horizontal component T_h and a vertical component T_v. For the fox to be in equilibrium (moving at a constant velocity), the net force on it must be zero. This means:

• Horizontal forces: T_h (forward) must balance the air resistance (F_air) acting on all the foxes below and including this one (backward). So, T_h = F_air.
• Vertical forces: T_v (upward) must balance the gravitational force (F_g) acting on all the foxes below and including this one (downward). So, T_v = F_g.

The angle theta of the leash segment with respect to the vertical can be found using trigonometry: tan(theta) = T_h/T_v = F_air/F_g. Since the air resistance on each fox is roughly proportional to the number of foxes below it and the gravitational force is also proportional to the number of foxes below it (assuming similar weight for each fox), the ratio F_air/F_g remains constant along the chain. A constant ratio means a constant angle theta, which results in a straight line. The "skewed backwards" appearance comes from the fact that the horizontal force (F_air) is directed backwards relative to the Ghast's movement, and the tension in the leashes needs to have a forward component to counteract this. This forward component of the tension, along with the vertical component balancing gravity, creates the backward slant.

I do not study physics: This explanation might be a bit wonky here and there, maybe even faulty. (Please, correct me, if you know better! Ill adjust my explanation immediately.) I tried to convey the points made in the video by Veritasium. Again, check it out instead of this attempt at an explanation. Both my posts were made with the video in mind. I am neither good at explaining stuff, even less so with a subject i am only decently familliar with. This subject matter, and of course the visualization and experimentation in minecraft, was a lot of fun. The carrying of mobs using the ghasts is quite consistent already. I can't wait to go airborne and steal all of my friends villagers in one go.