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Semester one assignment: Find the angular speed

  1. Mar 9, 2009 #1
    1. The problem statement, all variables and given/known data
    A thin rod of lenth 1.5m is oriented vertically, with its bottom end attached to the floor by means of a frcitionless hinge. The mass of the rod may be ignored compared to the mass of and object ixed to the top of the rod. The rod, starting from rest, tips over and rotates downward. What is the angular speed of the rod just before it strikes the floor?

    2. Relevant equations

    3. The attempt at a solution
    I need to find the time taken for the rod to hit the floor. I don't have enough information to use the equations of rotational kinematics without time. I can't use the equations of uniform circular motion, because the object is accelerating tangentially. I could break down the x and y motion of the object attached to the rod, but the conditions are not of free fall, surely? If I do treat the object as freefalling, it's very easy to get the time taken to hit the floor. Is that the correct way to get the time? Can I treat it as an object in free fall?
  2. jcsd
  3. Mar 9, 2009 #2


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    Welcome to PF!

    Hi invadertak! Welcome to PF! :smile:
    No … just use conservation of energy :wink:
  4. Mar 10, 2009 #3
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