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Homework Help: Particle constrained to move on a sphere

  1. Sep 3, 2009 #1
    1. The problem statement, all variables and given/known data
    A particle of mass m is constrained to move on a sphere of radius R by an applied force F(theta,phi). Write the equation of motion.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 3, 2009 #2


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    Hi dray. Welcome to PF.

    Forces are vectors. How would you write the given force as a vector? What does the problem say? Is this a force in the radial direction only or does it have angular components?

    What does your attempt at a solution represent? It cannot be an expression of Newton's Second law because the "del" operator has to do with spatial derivatives and the Second Law involves a second time derivative.

    Your relevant equations should be

    x = R sinθ cosφ
    y = R sinθ sinφ
    z = R cosθ

    There is no explicit time dependence in these expressions, but theta and phi themselves are functions of time.
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