Air is streaming past a horizontal air plane wing such that its speed is `120 ms^-1` over the upper surface and `90 ms^-1` at the lower surface. If the density of air is `1.3 kg m^-3`m find the difference in pressure between the top and bottom of the wing. If the wing is `10 m` long and has an average width of `2 m`, calculate the gross lift of the wing.

Explanation

To solve the problem, we will use Bernoulli's equation to find the pressure difference between the upper and lower surfaces of the wing, and then calculate the gross lift based on that pressure difference.

### Step 1: Identify the given values
- Speed over the upper surface (B2) = 120 m/s
- Speed over the lower surface (B1) = 90 m/s
- Density of air (ρ) = 1.3 kg/m³
- Length of the wing (L) = 10 m
- Width of the wing (W) = 2 m
...