New answers tagged perpetual-motion
The answer comes from definition of perpetual motion. In must require no energy input. You however, do use energy by throwing the screwdriver. Eventually, without a source of calories, you will run out of energy.
Ignoring many of the limiting factors of this problem (like air and water resistance), this wouldn't do what you think it would because the screw driver would travel around Earth and come back to you from the opposite direction. When you catch it again, it would slow you down again by the same amount that throwing it sped you up. You'd come to a halt. So ...
The force that the seal has to keep water from escaping must have the same force as the balloon being pushed upwards at least, this will cause it to stop the balloon from going upwards and no motion will occur.
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