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Homework Help: Instantaneous Acceleration?

  1. Jun 1, 2010 #1
    A child on a Ferris wheel is moving vertically upward at 6.20 m/s at one instant, and 0.150 s later is moving at 6.20 m/s at an angle of 41.5° above the horizontal. Estimate the child's instantaneous acceleration.
    What is the magnitude?
    What is the direction? (degrees below the horizon)

    I tried using the equation
    ax=V(cos)THETA - Vinitial/TIME
    Then taking the squareroot of the two answers above squared, but this did not work. where am i going wrong?
  2. jcsd
  3. Jun 1, 2010 #2


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    Think centripetal acceleration. The child is moving in a circle at constant speed (no tangential acceleration or tangential acceleration components)..
  4. Jun 1, 2010 #3


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    The angle is given with respect to the horizontal direction, which you used as x direction. Initially, the child moves vertically upward, so there is a non-zero initial velocity component in the y direction and the initial x component of the velocity is zero.

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