News

Loading...

Wednesday, July 12, 2006

Vacuums: They Don't Suck!

I've been reading nature books lately, since I'm spending the summer in the woods and want to figure out what's around me. In one, I read a description of how the low pressure in a tornado "sucks things in." Another mentioned that "nature abhors a vacuum."

But comparatively low pressure does not exert any sort of force on anything at all. After all, it's low pressure. This was an ancient error -- "nature abhors a vacuum" comes from the middle ages -- and was refuted by Pascal in a famous experiment. There is no "pull" from a vacuum or low pressure system -- there is a "push" from the higher pressure around it. That is why mercury does not rise as high in an evacuated tube on a mountaintop as it does at sea level -- the vacuum is the same in both cases, so if it "pulled," the mercury should go just as high in both places. It doesn't, because there is more air pushing it up at sea level.

7 comments:

  1. Didn't the Catholic Church burn Hoover (the inventor of the vacuum) at the stake?

    Seriously, would a vacuum cleaner work on the moon? What about a siphon? (I asked Cecil that but the wuss dodged the question.)

    ReplyDelete
  2. No, a vacuum cleaner won't work in a vacuum--unless you just want the brush on it to sweep moon dust into the bag, which it will do to some extent.

    The motor will just spin really fast (like a shop vac does if you block the intake) but of course you won't be able to hear it. It's possible it will spin fast enough to destroy the impeller.

    ReplyDelete
  3. So here's a plan -- bring your house to Jupiter on cleaning day, and your vacuum cleaner will work really well.

    ReplyDelete
  4. Don't be silly, Gene. The plug wouldn't work with the outlets on Jupiter. I guess you could use the dustbuster if it had a good charge.

    ReplyDelete
  5. That's why I recommended bringing the whole house -- that way you have the outlets with you.

    ReplyDelete
  6. Yeah I realized that too after Blogger finally decided to "run" my second comment. (I posted it and it seriously took over 24 hours to show up.) Actually, most of my jokes are up to 45% funnier before I say or type them.

    ReplyDelete
  7. Blogger was trying to save you the embarrassment.

    ReplyDelete