What caused the flying pig to move in a circle, the vertical component of the tension, the horizontal component of the tension, the weight, or a mysterious unknown thing called the centripetal force?

Answer: The centripetal force

Explanation:

Refer to the diagram shown below.

T = the tension in the rope

m = the mass of the flying pig

v = the tangential velocity of the pig

r = the radius of the circular motion

F = the centripetal force

The centripetal force is due to the centripetal acceleration of

a = v²/r.

Therefore the pig flies in dynamic equilibrium under the action of the three forces:

mg, the weight of the pig

T, the tension in the rope

F = (mv²) / r, the centripetal force