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Homework Help: The Conical Pendulum

  1. Mar 12, 2007 #1
    The Conical Pendulum

    A small object of mass m is suspended from a string of length L = 1.8 m. The object revolves in a horizontal circle of radius r with constant speed v and angle = 28°

    Find the speed of the object.
    i found s=v=2.098.

    Find the period of revolution, defined as the time interval required to complete one revolution.
    i found it to be ... t=2.53


    For the conical pendulum described above, determine the following if m = 14.0 kg.
    (a) the horizontal and vertical components exerted by the string on the object
    (b) the radial acceleration of the object.

    for H my equation is
    T=ma/sin theta

    and to find a=s/t
    i take what i found in the previous problem right?
    so s=v=2.098
    and t=2.53?

    and for Fv my equation is T=mg/costheta?

    and then for part b...mv^2/r...
    but what is r?

    OKAY i found everything BUT the HORIZONTAL COMPONENT!!!
    Last edited: Mar 12, 2007
  2. jcsd
  3. Mar 13, 2007 #2


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    Staff Emeritus
    Science Advisor
    Gold Member

    For the first part I get a slightly different answer for the speed and period. your answers are round about the same as mine so perhaps just using different constants.

    For parts a and b, you will have to go back to the circular motion equations and find the horizontal force being exerted on the bob.

    part b the equation you have used is for force but you want acceleration. Remember F=ma. Also you should know what r is from the first part of the question. Its simply a matter of trigonometry (i.e. the pendulum string forms a right angled triangle with the vertical and horizontal and you know the hypotenuse and one of the angles).
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