What mainstream air velocity parallel to a surface is required to dislodge a

$10-m$ standard$-$density sphere from that surface?$//$Assume a laminar bound$-$

ary layer $0\mathrm{.}1$ mm thick having a linear velocity gradient. For simplicity, as$-$

sume that the particle is dislodged when the drag force for the velocity at the

centerline of the particle equals $0\mathrm{.}01$ times the adhesive force. The relative

humidity is $50\%.$ Assume that Stokes's law holds.

ANSWER: $110\frac{m}{s}[11,000c\frac{m}{s}].$b