1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Hourglass's weight

  1. Dec 7, 2014 #1
    How does an hourglass's weight change while sand is dripping in it? (better be in a diagram)
     
  2. jcsd
  3. Dec 7, 2014 #2
    Start by saying what you think "weight" is and why it should be changing.
     
  4. Dec 7, 2014 #3
    W=mg that is what weight is. I think that when the sands are falling it is a kind of free fall; so some of the hourglasses's weight should diminish.
     
  5. Dec 7, 2014 #4
    OK.

    There is nothing about falling, free or otherwise, or not falling at all, in the definition above. Why should the weight change then?
     
  6. Dec 7, 2014 #5
  7. Dec 7, 2014 #6
    That experiment does not measure the weight as you defined it in #3.
     
  8. Dec 7, 2014 #7
    OK then, whatever it is just explain it!
     
  9. Dec 7, 2014 #8
    The truth is that experiment measures the tilt of the scales (which they call "weight reading"), and nothing else.

    They explain why that "reading" is different from the static case. The details are complicated, and depend not only on the motion of the sand, but on the motion of the pans, too.
     
  10. Dec 7, 2014 #9
    Can you demonstrate it in a diagram?or give a link of it?
     
  11. Dec 7, 2014 #10

    Danger

    User Avatar
    Gold Member

    You're pretty demanding for someone with no bargaining leverage. :oldgrumpy:
     
  12. Dec 9, 2014 #11

    A.T.

    User Avatar
    Science Advisor
    Gold Member

  13. Dec 9, 2014 #12

    Danger

    User Avatar
    Gold Member

    I've never actually heard of this particular question before, but it is really reminiscent of the one about jumping in an elevator or birds flying inside a truck.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Hourglass's weight
  1. Hourglass on the Moon (Replies: 5)

  2. Apparent weight (Replies: 51)

  3. Weight concept (Replies: 9)

Loading...