InterviewSolution
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InterviewSolution
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Air is streaming past a horizontal air plane wing such that its speed is `120 ms^-1` over the upper surface and `90 ms^-1` at the lower surface. If the density of air is `1.3 kg m^-3`m find the difference in pressure between the top and bottom of the wing. If the wing is `10 m` long and has an average width of `2 m`, calculate the gross lift of the wing. |
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Answer» Correct Answer - [`4095 Nm^(-20; 81900N`] Here, `v_(1)=120 ms^(-1), v_(2)=90 ms^(-1)`, `rho=1.3 kf m^(-3), l=10.0m , b=2.0m ,` Let `P_(1)` and `P_(2)` be the pressure of air at the upper and lower faces of plane respectively, then `(P_(1))/(rho)+(1)/(2)v_(1)^(2)=(P_(2))/(rho)+(1)/(2)v_(2)^(2)` `:. P_(2)-P_(1)=(1)/(2)rho (v_(1)^(2)-v_(2)^(2))` `=(1)/(2)xx1.3xx(120^(2)-90^(2))=4095 Nm^(-2)` Gross lift `=(P_(2)-P_(1))xxA=(A=(P_(2)-P_(1))xxlxxb` `=4095xx10xx2=81900 N` |
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