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!

Homework Help: Your physics teacher has asked you to build a barometer

  1. Oct 27, 2016 #1
    1. The problem statement, all variables and given/known data
    . Your physics teacher has assigned you the task of building a water ba,rometer. You've learned that the pressure of the atmosphere can vary by as much as 5 percent from 1 standard atmosphere as the weather changes. (a) What minimum height must your ba,rometer have? (b) One stormy day the TV weather person says, "The barometer pressure this afternoon is low 29.55 inches." What is the height of the water in your barometer?

    2. Relevant equations

    I'm not really sure where to even begin
    3. The attempt at a solution
    I have none, don't know where to start. There is no mention of a barometer in my textbook.
  2. jcsd
  3. Oct 27, 2016 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If I say to you, "Inches of mercury," does it ring any bells?
  4. Oct 27, 2016 #3
    not really. I mean I know that barometers use mercury.
  5. Oct 27, 2016 #4


    User Avatar

    Staff: Mentor

    Perhaps do a little browsing/research on the web? There are lots of articles that discuss barometers and how they work. I suspect that the question is asking about a simple sealed-tube barometer (tube sealed at top end, filled with fluid and standing open-end-down in an open container of the same fluid).
  6. Oct 27, 2016 #5
    okay so how would the atmosphere differing up to 5% be related to the height of the barometer?
  7. Oct 27, 2016 #6
    would this require taking a derivative?
  8. Oct 27, 2016 #7


    User Avatar

    Staff: Mentor

    What holds up the column of fluid in a barometer? What forces (or pressures) are balanced?

    No. Just some calculations of pressures (air and fluid).
  9. Oct 31, 2016 #8


    User Avatar
    Homework Helper

    A barometer measures air pressure.
    It does so by balancing the air pressure with the pressure exerted by a column of fluid.
    When to two pressures are equal the height of the fluid column is an indication of the ambient air pressure.
  10. Oct 31, 2016 #9
    got it, thanks for the help everyone!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted