Calculate the drag of a smooth sphere of \(0.5 \mathrm{~m}\) diameter when placed in an airstream \(\left(15^{\circ} \mathrm{C}\right.\) and \(\left.101.3 \mathrm{kPa}\right)\) if the velocity is

(a) \(6 \mathrm{~m} / \mathrm{s}\), 

(b) \(8.4 \mathrm{~m} / \mathrm{s}\). For the same drag coefficient as at \(8.4 \mathrm{~m} / \mathrm{s}\), at what velocity will the sphere attain the same drag that it had at a velocity of \(6 \mathrm{~m} / \mathrm{s}\) ?