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Homework Help: There's a chopstick on my hand. I need to find the 'angles'.

  1. Feb 10, 2010 #1
    1. The problem statement, all variables and given/known data
    Known:
    - Mass of the chopstick
    - Gravity

    2. Relevant equations
    ed0ec2ed1783f9c2654b4acf7d432bec.png
    c22e37af0377d584aea9ff3cfadf7332.png
    8fd728988b0b1704566656584a280601.png

    So the alpha(angular acceleration) can be found

    3. The attempt at a solution
    By knowing angular acceleration, I successfully wrote a program that simulate a chopstick falling onto my hand. But all of this is assuming my hand didn't move at all. Currently in my simulation, only the gravitational force affect the angle change (angular acceleration).

    My question:
    How my hand affect the angular acceleration?
    I have these data:
    - My hand's acceleration in x, y and z axis.
     
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Feb 10, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi lgmcben! Welcome to PF! :wink:

    Your hand will exert a force F, which wiill increase the linear acceleration by F/m, and will also add a torque. :smile:
     
  4. Feb 10, 2010 #3
    Re: Welcome to PF!

    Hi. Thank you for your answer. =)

    I'm sorry I forgot to mention that I want to omit any linear translation in this simulator ^_^; I only need to simulate the angular-related translations.


    I have one more question:
    Does this torque equal to
    c22e37af0377d584aea9ff3cfadf7332.png
    Where
    F = ma
    and
    m = mass of the chopstick
    a = acceleration of my hand in x axis? (if x, y and z axis is too much, then let's talk about only x axis for now)

    Thank you again!
     
    Last edited by a moderator: Apr 24, 2017
  5. Feb 10, 2010 #4
    Yes it does equal to the above specified equation. However, you will need to consider torquing about the centre of mass in the chopsticks if the pivot points are anything except the middle of the chopsticks (assuming mass to be equally distributed and the chopsticks to be rectangular prisms)
     
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