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!

Time for a Droplet of Water to Fall .25m from Hole

  1. Nov 27, 2012 #1
    Time for Droplet of Water to Fall .25m from Hole

    1. The problem statement, all variables and given/known data

    A cylindrical tank .7m tall is filled with water and placed on a stand (below it) that is .3m tall. A hole of radius .001 m in the bottom of tank is opened. Water then flows through the hole and through an opening in the stand and is collected in a tray .3 m below the hole. At the same time, water is added to the tank at an appropriate rate so that the water level in the tank remains constant.
    Find:
    ^The speed at which the water flows out from the hole
    [Done: 3.7 m/s]
    ^The volume rate at which water flows out from the hole
    [Done: 1.1623893 x 10-5 m3/s]
    ^The volume of water collected in the tray in 2 minutes
    [Done: .0013948672 m3]
    ^ ! The time it takes for a droplet of water to fall 0 .25 m from the hole.

    2. Relevant equations

    Density of Water: 1000 kg/m3

    3. The attempt

    - PART D -

    *The time it takes for a droplet of water to fall 0 .25 m from the hole.
    ΔX = V°*t + (1/2)*a*t2
    -
    .25 = 3.7t + (1/2)(9.8)t2
    -
    4.9t2 + 3.7t - 0.25 = 0
    - Used Quadratic Equation but answer turned out negative and does not match answers -
    ? ? ?
    Correct Answer: 0. 062 seconds
    My question is how.
     
    Last edited: Nov 27, 2012
  2. jcsd
  3. Nov 27, 2012 #2

    gneill

    User Avatar

    Staff: Mentor

    Re: Fluid Motion

    Show your quadratic formula workings. Something must've gone awry, because I get two results and one of them matches the expected value.
     
  4. Nov 27, 2012 #3
    I pretty much laid out the whole schema. I know the quadratic equation I provided gives answers that do not match the correct one (as I stated earlier). However, I'm not sure if I'm even supposed to use the kinematics equation listed above in order to solve the problem.
    The answer may even be 0.021 seconds but my professor informed me that 0.021 was not the answer and promptly replaced the old answer with 0.062 seconds.
     
  5. Nov 27, 2012 #4

    gneill

    User Avatar

    Staff: Mentor

    The method is fine. What I'm saying is, something went wrong in your application of the quadratic formula. as I obtained the correct result using the same starting point.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Time for a Droplet of Water to Fall .25m from Hole
Loading...