Q.

A fully loaded Boing aircraft has a mass of 5.4×105 kg. Its total wing area is 500 m2. It is in level flight with a speed of 1080 km/h. If the density of air ρ is 1.2 kg m-3, the fractional increase in the speed of the air on the upper surface of the wing relative to the lower surface in percentage will be (g=10 m/s2)         [2023]

1 16  
2 6  
3 8  
4 10  

Ans.

(4)

P2A-P1A=5.0×105×g

P2-P1=5.4×106500=5.4×2×102×10=10.8×103

P2+0+12ρV22=P1+0+12ρV12

P2-P1=12ρ(V12-V22)=12ρ(V1-V2)(V1+V2)

10.8×103=12×1.2(V1-V2)×2×3×102

10.8×10=3.6(V1-V2)

V1-V2=30

(V1-V2V)×100=30300×100=10%