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Homework Help: Oscillation AND SHM

  1. Feb 28, 2008 #1
    We want to support a thin hoop by a horizontal nail and have the hoop make one complete small-angle oscillation each 2.0s .

    What must the hoop's radius be (in meters) ?


    An object is undergoing SHM with period 0.260 s and amplitude 5.55 cm. At t=0 the object is instantaneously at rest at x= 5.55 cm.

    Calculate the time it takes the object to go from x= 5.55 cm to x= -1.55 cm.

  2. jcsd
  3. Feb 28, 2008 #2


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    Homework Helper

    what's the moment of inertia of a hoop about its center?

    what's the moment of inertia of a hoop about its rim? (use parallel axis theorem)

    where is the center of gravity of the hoop?

    what is the force due to gravity on the hoop?

    what is the torque on the hoop?

    what is the equation relating torque to angular acceleration?

    what is the small angle approximation for the sine function?

    your caps lock key is stuck, maybe?
  4. Feb 29, 2008 #3
    For the second question, start with the general equation of motion of an shm. Do you know what that is?
  5. Feb 29, 2008 #4
    in my questions that all they gave you i need like a answer lol and some work i cant figure these two out thats all
  6. Mar 1, 2008 #5
    The equation describing shm is given by y=asin(wt+c), where y is the displacement, w is the angular frequency, t is time and c is the phase difference. Lets start with what you do know about shm. Any thoughts on how to go about this? Not mathematically, just conceptually.
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