Answer:
shearing force is [tex]3.40\times 10^{-4} lb[/tex]
Explanation:
we know that
force can be determined [tex]F = \tau \times A[/tex]
Area can be determine as
[tex]A = \frac{\pi}{4} d^2 = \frac{\pi}{4} [\frac{0.2}{12}]^2 = 2.18\times 10^{-4} ft^2[/tex]
linear velocity can be determines as
[tex]\tau = \mu_{air} \frac{U}{b}[/tex]
dynamic viscosity of air [tex]\mu_{air} = 3.74\times 10^{-7} lb-s/ft^2[/tex]
veolcity of disc
[tex]U =\omega R[/tex]
[tex]U = \frac{2\pi N}{60} \times R = \frac{2\pi 10,000}{60} \times \frac{2}{12}[/tex]
U = 174.5 ft/s
so
[tex]\tau = 3.74\times 10^{-7} \times \frac{174.5}{\frac{0.0005}{12}}[/tex]
[tex]\tau = 1.56 lb/ft^2[/tex]
[tex]F = 1.56\times 2.18\times 10^{-4} = 3.40\times 10^{-4} lb[/tex]
shearing force is [tex]3.40\times 10^{-4} lb[/tex]
