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Force to Open A Door

  1. Apr 10, 2008 #1
    Please can one of you brainy people out there help me. I need to work out the force to open a door when there is a 60pascal pressure acting against it.

    The size of the door is 1000mm wide x 2000mm high.
    The differential Pressure is 60 pascals
    The handle is 70mm away from the leading edge of the door.

    Ideally I need the calculation so I do the calc myself on future projects.

    I did find the attached documents, just not fully sure what figures to use where.

    Any help would be much appreciated.
  2. jcsd
  3. Apr 10, 2008 #2
    The area of the door is:
    A = 2 m2
    Force = A [tex]\Delta[/tex]p​
    This force acts at the center of the door.
    Now that you have a force and its point of application, you can calculate the value of the counteracting force at the handle.

    Hint: consider moment equilibrium at the door's hinge.

    It only works at the time zero, before the door starts to rotate. After that, the air starts to leak in (or out) and things get quite nasty, involving a 3D fluid dynamics.
  4. Dec 20, 2009 #3
    I agree with the last post, but If there is a handle to open too you will have more than one equation, first torque times distance to open the handle and then.... carry on with the last comment unless I have missed the point. Also I don't thing think the pressure will effect the center of the door, but the centroid of the door. But what do I know I am just a dumb college student.
  5. Dec 24, 2009 #4
    Guys, thanks for all your help so far, but I am still unsure what the force to open my door is. Could one of you spell it out for me in very simple terms and do the calculation so I can see what the answer is and how to do it.

  6. Dec 24, 2009 #5


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    Staff: Mentor

    Most doors are rectangular, some are round - in both cases centers are in the same point. So while you are in general right, it doesn't matter.
  7. Dec 24, 2009 #6


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    Staff: Mentor

    You need to calculate force acting on the door - that is, pressure times surface area. Then you have a second class lever at work.
  8. Dec 24, 2009 #7
    Okay, so

    A = 2 m2
    Force = A (delta)p

    Force = 2 x 60
    Force = 120Pa

    If 10 Pascals is equivalent of 1Kg of force /M2

    Force = 12Kg (to open door - exluding application of second class lever)
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