﻿ Air is streaming past a horizontal aeroplane wing such that its speed is 120 ms–1 at the upper surface and 90 ms–1 at the lower surface. If the density of air is 1.3 kg/m3, find the difference in pressures between the two surfaces of the wing. If the wing is 10 m long and has an average width of 2 m, then calculate the gross lift on it.       : Kaysons Education

# Air Is Streaming Past A Horizontal Aeroplane Wing Such That Its Speed Is 120 Ms–1 at The Upper Surface And 90 Ms–1 at The Lower Surface. If The Density Of Air Is 1.3 Kg/m3, Find The Difference In Pressures Between The Two Surfaces Of The Wing. If The Wing Is 10 m long And Has An Average Width Of 2 M, Then Calculate The Gross Lift On It.

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## Question

### Solution

Correct option is

4095 N/m2, 81900 N

By the principle of continuity and the Bernoulli’s theorem, the difference in pressure between the upper and the lower surface of the aeroplane wing is

Here v1 and v2 are speeds of air streams at upper and lower surface respectively, and  is density of air.

Substituting the values :

.

If the area of the wing is A, then the gross lift on it is

= 81900 N.

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