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abrenner
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Not sure if this is the correct forum, but I'm sure someone will let me know. My question regards Newton's 3rd law of motion. How does Newton's 3rd law relate to a sailboat moving downwind. (I'm not talking about lift, or Bernoulli's principle, just a simple single sail, let all the way out, with the wind behind it. As I understand the 3rd law, the wind impinges on the sail, and the sail pushes the wind back. So far, the forces cancel. However, if the sail pushes back on the wind and the sail is attached to the boat, the boat moves forward. Am I correct so far? If so, where is the equal and opposing force on the boat? Is it the drag produced by the water? If it is equal, why does the boat move at all?? I suspect it has to do with the 2nd law and unequal masses, i.e., the mass of the boat vs. the mass of the water? If the mass of the water is less, then the boat will accelerate? Am I all wet(pardon the pun) here? If not, how can you possibly determine the mass of the water?
A. Brenner
A. Brenner