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Comment by fritzo

1 day ago

Could you pick up, say, a manhole cover?

Mythbusters lifted a 2 ton car using a consumer grade vacuum cleaner. the math is this: the air pressure over 1 sq meter is about 10 tonnes, so if make a box with that area and reduce the pressure by 0.25 atm, you get a force of equivalent to 2.5 tonnes, enough to lift the car.

https://www.youtube.com/live/GbqKwPktCdo?xstg=CAMSBhUDze3xHw...

Atmospheric pressure is around 14psi, at a rough guess a manhole cover is around 200lbs so you'd need just a little over 14sq in to make that work.

Sure, why not?

The seal won't be perfect so you'll be running the pump more or less continuously. Apropos manhole covers: I wonder what would happen if this car would drive over one. Or was that your point?

  • This is why they temporarily spot weld manhole covers before street races.

    • Yes, and those don't have fans underneath, that's just the ground effect. This is probably far worse. I also wonder how large the intake holes are because you can easily imagine what the effect would be pulling that trick on a road surface that's not perfectly clean.