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Homework Help: Principle of impulse and momentum

  1. Nov 22, 2014 #1
    1. The problem statement, all variables and given/known data

    In the gear arrangement shown, gears A and C are attached to rod ABC,
    which is free to rotate about B, while the inner gear B is fixed. Knowing
    that the system is at rest, determine the magnitude of the couple M which
    must be applied to rod ABC, if 2.5 s later the angular velocity of the rod is
    to be 240 rpm clockwise. Gears A and C weigh 2.5 lb each and may be
    considered as disks of radius 2 in.; rod ABC weighs 4 lb
    2. Relevant equations

    Syst. Momenta 1 + Syst. Ext. Imp. 1→2 = Syst. Momenta

    3. The attempt at a solution: I draw external drives like this.

    However in Figure 2 corresponds to the solution of the problem, they draw only two forces: P and Q , but I don't really understand how they simplify all other forces in only one force Q (weight and reactions on the pin to get to that)

  2. jcsd
  3. Nov 27, 2014 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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