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Calculating my door's mass

  1. Jan 6, 2007 #1
    I am trying to calculate the mass of my wooden room door without taken them off their hinges using the torque and angular acceleration formulas.
    I have ang. acc. (how much time passed calculated when door passed certain radian by certain push from me).
    Rotational inertia is calculated by treating the door as flat area (metal locking has been taken into consideration -but not the friction force from hinges, I guess they're well oiled and fraction can be neglected, right????)

    The problem is the force I applied. How can I measure it accurately?
    If I could find a way to do it I can easily measure the door's mass.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jan 6, 2007 #2


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    How about a spring balance?
  4. Jan 6, 2007 #3
    elaborate please
  5. Jan 6, 2007 #4


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    Look it up. It's a spring with some form of attachment at either end and a calibrated gauge in the middle to show how much the spring is stretched (hence reading off the force via Hooke's law).
  6. Jan 6, 2007 #5
    there is a way to measure the mass of the door without measuring force. however, it still requires a strong spring:

    Simple Harmonic oscillation.

    you just need to know k, and then count the period!
  7. Jan 6, 2007 #6
    taking the door off the hinges and putting it on a weight scaler would be easier perhaps but that's NOT the point, this method can be applied to situations where no other way of calculation is possible. Besides, it's fun.
  8. Jan 11, 2007 #7
  9. Jan 11, 2007 #8


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    Why do you want to do this determination? Is it for a school project?
  10. Jan 11, 2007 #9
    I study Physics at leisure. It's my hobby. Solving problem and contemplating about the world we live in makes me feel good, that's all.
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