Would this work?

Ringo · #1 11-01-2007, 05:06 PM

Imagine I'm sitting in a sailboat, and have a battery operated fan. I point the fan at the sails - will the boat move forward? What if the fan has an external power source?

Is that like pulling yourself up with your own shoelaces?

Sephus · #2 11-01-2007, 05:14 PM

[ QUOTE ]

Imagine I'm sitting in a sailboat, and have a battery operated fan. I point the fan at the sails - will the boat move forward? What if the fan has an external power source?

Is that like pulling yourself up with your own shoelaces?

[/ QUOTE ]

it wouldn't work. the fan would push you backward more than forward. if you turned the fan around and pointed it behind you (like a fanboat) i think it would help you a bit.

billygrippo · #3 11-01-2007, 05:14 PM

the fan would make an equal amount of force in the opposite direction.

hitch1978 · #4 11-01-2007, 06:45 PM

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Is that like pulling yourself up with your own shoelaces?

[/ QUOTE ]

Yes.

mbillie1 · #5 11-01-2007, 07:14 PM

lol perpetualmotionaments

eviljeff · #6 11-01-2007, 09:03 PM

http://archiveserver.twoplustwo.com/...page/0/fpart/1

DanielM · #7 11-01-2007, 09:08 PM

Actually, it would work. There is force being generated on both sides of the fan, but on one side the sail is catching it, on the other side only minor air turbulence is there to resist the force.

billygrippo · #8 11-01-2007, 09:16 PM

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Actually, it would work.

[/ QUOTE ]

incorrect

stormstarter28 · #9 11-01-2007, 09:17 PM

Question: how are you getting internet access if you're stranded on a sailboat?

Sephus · #10 11-01-2007, 10:04 PM

[ QUOTE ]
Actually, it would work. There is force being generated on both sides of the fan, but on one side the sail is catching it, on the other side only minor air turbulence is there to resist the force.

[/ QUOTE ]

the fan is pushing the air forward. you're pushing the fan forward. the boat is pushing the bottoms of your feet forward. you're pushing the boat backward just as hard as the fan is pushing forward on the air. that's how you stay on the boat (see: newton's 3rd law of motion).

so in order to have a net forward force, the air has to push on the sail harder than the fan is pushing on the air. you're never going to get 100% of that kinetic energy from the fan to the air back into the sail.

the boat is going backwards.