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I was asked a bit trivial question, but am failing to decide what is the right answer.

Suppose I have a balloon [inflated with a lighter than air gas] and a strip, maybe a very light flag attached, as in the images.

This balloon as dragged (is this a right English word for the process?) by the wind. From right to left in the image.

How would it look like? Will the flag be "behind" or "right under" the balloon? Will it point forward or backward during the motion?

I think that one possibility is impossible, that the flag will be in forward position, but pointing backward.

Balloon with forward flag pointing forward Balloon with underneath flag pointing backward Balloon with underneath flag pointing forward Balloon with backward flag pointing backward Balloon with backward flag pointing forward

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  • $\begingroup$ I think the fifth image shows what is going to happen. $\endgroup$ Mar 2, 2020 at 15:34
  • $\begingroup$ why do you nor just try it out, the experiment is not very expensive. $\endgroup$
    – trula
    Mar 2, 2020 at 15:36
  • $\begingroup$ Does the flag touch the ground or not? $\endgroup$
    – rghome
    Mar 2, 2020 at 15:45
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    $\begingroup$ Is the wind velocity constant? $\endgroup$
    – PM 2Ring
    Mar 2, 2020 at 16:12
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    $\begingroup$ Re, "This balloon is dragged by the wind." A more useful way to think about it: The "wind" is a moving mass of air. The balloon is embedded in the air mass. $\endgroup$ Mar 2, 2020 at 16:28

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As any pilot can tell you, once you are up in the air, whether there is wind or not doesn't really change anything (as long as it is steady).

Wind is air moving relative to the ground, but if you don't care about the ground (imagine you can't see it) then the balloon doesn't know whether the air is moving or not (assuming the wind velocity is constant and consistent).

So everything just hangs straight down (none of the pictures are correct).

UPDATE: You will, of course, find photographic evidence showing balloons with tails blowing in all kinds of directions. In reality, the situation will be more complicated than I said. If the balloon is initially accelerated after being let go (either sideways or upwards) then the tail will tend to lag behind the balloon (assuming the balloon has more lift and air resistance). There are also gusts, vortices and wind-shear. Wind speed tends to increase with height due to the loss of shelter from buildings and trees. So my requirement of "constant and consistent" wind speed may not occur.

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