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5

From the geometry, you can state that in order to move the screw by 1 unit of distance, you have to move the end of the handle by $10\times 20\times 2\pi$ units of distance. Let's call the unit of distance $[L]$ - in this case, an inch might be a good unit but we don't have to be explicit about that. Conservation of energy says that work done on the system ...

16

Work is calculated as force times distance. $$W = Fd$$ The purpose of a simple machine like a screw jack is to lessen the force required. However, the work needed is still the same, so the distance over which you exert the force has to increase. Halving the force requires doubling the distance. In this problem, you want to lift 2000 lbs a distance of 1 ...

1

The real problem with a workable anti-gravity device (assuming it could be made) is how to power it. It will most likely need an electrical power supply. For example, a Boeing 747 needs about 100MW of power to get into the air, and it's thrust to weight ratio is about 1:6 which means that your anti-grav installed on a 747 would need a half gigawatt power ...

1

There's a lot of reasons why we can't fly like superman/Rocky the Squirrel/birds. We should note the flying involves movement through the air controlled by the flyer which can carry on indefinitely. If you're looking for something else, you should know about squirrel suits and jet-packs. Lift is the number one reason why we can't use our arms to fly. The ...

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