$10\mathrm{.}29.$ A helium wind balloon with a diameter of $1\mathrm{.}1m$ is attached to the ground by a thin,

lightweight cable as shown in Figure $10\mathrm{.}35.$ The balloon has a weight of $1\mathrm{.}5N.$ The

balloon is filled with helium at a temperature and pressure of $20C$ and $101\mathrm{.}3$kPa.

respectively, and the surrounding air has the same temperature and pressure. The

weight and drag on the support cable is negligible. Under a particular wind speed.

the support cable is observed to deflect by $16$ from the vertical direction.

Figure $10\mathrm{.}35$: Wind balloon

Hint: You are required to find the wind velocity at which the balloon will have an angle of

$16.$ Choose the balloon as the free body diagram and analyse the forces on it$.$ The

drag can be evaluated using the relation we covered in the lecture note.