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Homework Help: Two Problems Dealing With Circular Motion

  1. Apr 3, 2005 #1
    1) A wheel is rotating at a rate of 2.7 revolutions every 3.0 s. Through what angle, in radians, does the wheel rotate in 1.0 s?

    I tried to solve this problem by:
    {a} 360 x 2.7 = 972
    {b} 972 / 3 = 324
    {c} 364 / (180 / Pi) = 5.65

    Yet, 5.65 is not the answer. The rust coated around the section of my brain labeled 'Trigonometry' is probably the culprit here.

    2) A highway curve has a radius of 127 m. At what angle should the road be banked so that a car traveling at 27.5 m/s has no tendency to skid sideways on the road? [Hint: No tendency to skid means the frictional force is zero.]

    I have no train of logic on this problem because I'm utterly spellbound. I feel as if perhaps I'm minus an essential formula, though.

    Any suggestions or advice would be a godsend.
  2. jcsd
  3. Apr 3, 2005 #2


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    I get 5.65 too.
  4. Apr 3, 2005 #3

    Doc Al

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    I think it is.

    No tendency to skid means that a frictional force is not required to keep the car from sliding.

    The car is centripetally accelerating. Consider Newton's 2nd law. (What forces act on the car?) Hint: The vertical components of the forces must add to zero.
  5. Apr 3, 2005 #4
    You're quoting two different numbers for the number of degrees per second, pick one!
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