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Homework Help: Domino Force

  1. Nov 25, 2014 #1
    1. The problem statement, all variables and given/known data
    I have dominoes of dimension 4.9 × 2.3 × 0.9cm and I want to know the minimum force it will take to knock it over and if there is an equation to calculate its speed and force

    2. Relevant equations
    I have attempted to use the torque formula but this was not successful as I did not know the torque force so i could substitute see below.
    3. The attempt at a solution
    Torque= F×4.9×sin 9.2726
  2. jcsd
  3. Nov 26, 2014 #2


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    What do you intend doing?
    Determine it experimentally or calculate it or both?
  4. Nov 26, 2014 #3
    To calculate it
  5. Nov 26, 2014 #4


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    If you interest is totally theoretically you may try looking at angular impulse:
    problem is its weight will also come into play once it starts toppling.
    Maybe one can calculate the amount by which its potential energy needs to be raised
    to lift its centre of mass to the top of the arc?
  6. Nov 26, 2014 #5


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    Gold Member

    andrevdh has addressed angular impulse and work, but the question says 'force', so I'll answer that.
    Draw a free body diagram of the standing domino. First you must decide where you are applying the force and at what angle to the horizontal. If you don't care about one or both of those, then I guess you wish to optimise that / those variables to find the minimum force. In that case, put in unknowns for the variables that can be optimised.
    Next it is a simple statics question: what force is needed to just tip the domino so that it is only touching the ground along one edge. You should be able to see that from this point on the force needed will diminish.
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