1. Not finding help here? Sign up for a free 30min 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!

Forces and Speed

  1. Apr 8, 2007 #1
    It takes 30.0s to fill a 2.00-L container with water from a hose with a constant radius 1.00cm. The hose is held horizontally. Determine the speed of the water being ejected from the hose.

    I have attempted this question, but I have got a different answer to my textbook. I may however be going about this the wrong way.

    Attempt:
    4p(0.01)/30^2 = 2pV/30
    V = 2.09E-3 m/s
     
  2. jcsd
  3. Apr 8, 2007 #2

    radou

    User Avatar
    Homework Helper

    What exactly does your attempt represent?

    How is the flow defined and how can you calculate it from the given data? Further on, how does the flow relate to the area and speed?
     
  4. Apr 8, 2007 #3
    oh yes - I was using acceleration formulae
    So, I should be using
    area = flow/velocity and flow = Litre/second
     
  5. Apr 8, 2007 #4

    radou

    User Avatar
    Homework Helper

    Try to do so.
     
  6. Apr 8, 2007 #5
    I have used that formula -
    velocity = (2/30)/(3.14*0.01^2) = 212.2m/s
    The thing is, my text book gives the answer as 21.2cm/s, and my answer converts to 2.12cm/s. Am I wrong or is the text book wrong?
     
  7. Apr 8, 2007 #6

    radou

    User Avatar
    Homework Helper

    Your answer is wrong.
     
  8. Apr 8, 2007 #7
    Okay - can you tell me where I went wrong, because I can't see where I went wrong
     
  9. Apr 8, 2007 #8

    radou

    User Avatar
    Homework Helper

    You went wrong with the flow units. 1 [L] = 1 [dm^3]. Convert to [cm^3].
     
  10. Apr 8, 2007 #9
    okay, thanks, I'll try again

    ~it's worked out, thanks for your help
     
    Last edited: Apr 8, 2007
  11. Mar 10, 2011 #10
    Sorry, a better question is why is area equal to flow / velocity and since 1 L equals 1dm wouldn't 1L equal to 10cm? So than why do we have r as 0.1?
    velocity = (2/30)/(3.14*0.01^2) = 212.2m/s

    Oh i see you are converting 1cm into dm. I still can't grasp how area = flow / velocity?
     
    Last edited: Mar 10, 2011
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Forces and Speed
  1. Forces and Speed (Replies: 24)

  2. Force and speed issues (Replies: 5)

Loading...