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!

Water pressure problem

  1. Jan 27, 2015 #1
    1. The problem statement, all variables and given/known data
    Water flows through a hole at the bottom of a tank that is filled to a height h=3m. The radius of the hole is r1 = 1.5 cm.
    1. What is the speed of the water immediately after it leaves the hole?

    2. At what distance d below the bottom of the tank is the radius of the stream reduced to r2 = 1 cm?


    2. Relevant equations


    3. The attempt at a solution
    I managed to solve the speed for 7.7 m/s. However, I'm not sure what formula to use to address the atmospheric pressure that cause the stream to shrink.
     
  2. jcsd
  3. Jan 27, 2015 #2
    The stream shrinks because it is accelerating gravitationally. As it speeds up, for the flow rate to remain constant, the cross sectional area must decrease.

    Chet
     
  4. Jan 27, 2015 #3
    Based on your clarification, I calculated the velocity at the bottom using the conservation of volumetric flow rate (R = Av = constant), v0 = 17.3. Then g = dv/dt -> dt = dv/g = 0.98 s. Then d = d0 + v0t + 0.5at2 = 12.3, which seems to be the correct result. What do you think?
     
  5. Jan 28, 2015 #4
    I haven't checked your arithmetic, but you seem to have the right idea.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Water pressure problem
  1. Water pressure homework (Replies: 14)

  2. Water Pressure (Replies: 2)

Loading...