If the speed of air flow past the lower wing of and airplane is 350 ft/s, what speed of flow over the upper wing will produce a lift of 20 lb/ft^2?

Explanation:

We shall apply Bernouli's theorem

ρgh + 1/2 ρ v² + P = constant

ρ is density of fluid ( here it is air ) v is velocity of air , P is pressure of air

For h to be constant

1/2 ρ v² + P = constant

1/2 ρ₁ v₁² + P₁ = 1/2 ρ₂ v₂² + P₂

P₂ -P₁ = 1/2 ρ₁ v₁² - 1/2 ρ₂ v₂²

P₂ -P₁ = Pressure difference = 20 x 32

ρ₁ and ρ₂ are same here and is equal to .07967 lb/ft³

Putting the values we get

20 x 32 = 1/2 x .07967 ( v₁² -v₂² )

( v₁² -v₂² ) = 16066

v₂ = 350 ft/s

v₁²-350²  = 16066

122500 + 16066 = v₁²

v₁² = 138566

v₁ = 372 ft/s

[ At lower wing velocity will be lower so that pressure will be higher.]

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)