Question

Hi everyone - i'm stuck on a homework question and would love some help!!

Can someone tell me how Bernoulli's principle works with a sail boat? I don't know how the force vectors resolve to push a sail boat faster into the wind than with the wind... thanks!

Answer 1

When you sail in roughly the direction of the oncoming wind, your sail will form a curved surface, like an airplane's upper surface, an airfoil. the air velocity on the outward curved (convex) surface is greater than that on the inner (concave) surface, so by Bernoulli's equation

p + (1/2) rho v^2 + rho g y = constant

the net pressure is from the convex to the concave side of the sail,
pushing the boat approximately forward.