In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wings are 70 m s⁻¹ and 65 m s⁻¹ respectively. If the wing area is 2 m², the lift of the wing is N. (Given density of air =1.2 kg m⁻³)

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810. Given: vᵤ=70 m s⁻¹, vₗ=65 m s⁻¹, wing area A=2 m², ρ=1.2 kg m⁻³. The air moves faster over the top, so the pressure there is lower and the wing feels a net upward push. Δ p=1/2ρ(vᵤ²-vₗ²)=1/2(1.2)(4900-4225)=0.6(675)=405 Pa. Lift =Δ p A=405×2. Lift =810 N.

In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wings are 70 m s⁻¹ and 65 m s⁻¹ respectively. If the wing area is 2 m², the lift of the wing is ______ N. (Given density of air =1.2 kg m⁻³)

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