Question

An airplane whose mass is 20000kg and whose wing area is 60m² is in level flight .what is the average difference in pressure between the upper and lower surfaces of its wings? Express the answer in PA?

Answer 1

For the airplane to remain in flight, the net force on it shall be zero.

But, Earth attracts it with a force equal to its weight.

The only other force to balance it could be the force due to the difference in pressure above and below it.

So, weight = pressure difference * area of wings.

Weight = mass * g = 20,000 kg * 10 m/s² = 200,000 N.

200,000 N = ΔP * 60 m²

So, ΔP = 200,000/60 N/m² = 10,000/3 N/m² = 3,333.33 N/m² or 3,333.33 Pa.