think about this...

[felson]

It looks like people are starting to agree somewhat on the airplane problem. So, how about this?

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I'm also confused why people say that the fan-on-skateboard contraption won't move because there is no net force on the system. Would you say the same thing if the sail were just 1 square centimeter in area? If not, then any explanation must take into account the size of the sail. I don't believe that has happened yet, except for some people who observed that the sail cannot capture all the moving air blown by the fan.

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