Air is streaming past a horizontal air plane wing such that its speed in 120 m/s over the upper surface and 90 m/s at the lower surface. If the density of air is 1.3 kg per metre3 and the wing is 10 m long and has an average width of 2m, then the difference of the pressure on the two sides of the wing of :

Explanation

To find the pressure difference between the upper and lower surfaces of the wing, we apply Bernoulli's equation. Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure. For the upper surface of the wing, the speed is 120 m/s, and for the lower surface, it's 90 m/s. Using the equation for pressure difference, ΔP = 0.5 * density * (v2^2 - v1^2), where v2 is the speed over the upper surface and v1 is the speed under the lower surface, we calculate ΔP = 0.5 * 1.3 * (120^2 - 90^2) = 4095.0 Pascal. Option A is correct. The other options are incorrect because they either misapply Bernoulli's equation or do not account for the correct difference in squared speeds.