The answer from the exam and demonstrated by Muller is B. The question is all about forces and so we need to look at what the rope is experiencing. It has a weight, it has a tension being attached to the helicopter, and since the helicopter is moving at constant velocity, it’s experiencing air resistance.
If the rope is divided into little segments, each will have a certain weight and experience the same air resistance, which is comparable to the weight of the rope. The segment at the bottom has little tension given its little weight. As we move up the rope the tension increases, reaching a maximum at the top.
But the direction of this tension and the direction of the rope doesn’t change because the weight is pulling the rope down and the air resistance is pulling the rope across, so their ratio stays the same. Changing the constant speed of the helicopter would change the strength of the air resistance and the direction of the rope but not its overall shape.
Muller loves going that little bit further however with these experiments and in the video actually reproduces the original version of the question (not used in the exam) that had a weight attached to the bottom of the rope. What do you think will happen to the rope in that case?
The shape changes as you would expect for little air resistance on the weight. And the right answer, in that case, is the shape marked as D.
