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Homework Help: Finding angular velocity of a car and period of a planet's rotation

  1. Mar 21, 2012 #1
    1. The problem statement, all variables and given/known data
    Part a: A newly discovered planet has a mean radius of 4030 km. A vehicle on the planet's surface is moving in the same direction as the planet's rotation, and its speedometer reads 169 km/h. If the angular velocity of the vehicle about the planet's center is 5.28 times as large as the angular velocity of the planet, what is the period of the planet's rotation?

    b: If the vehicle reverses direction, how fast must it travel (as measured by the speedometer) to have an angular velocity that is equal and opposite to the planet's?

    2. Relevant equations

    ω = (tangential v)/R

    T = 2∏/(ω)

    3. The attempt at a solution

    I have found that the angular velocity of the car is .0397 rad/h, and the angular velocity of the planet is .0075 rad/h (please confirm whether these values are correct!). For part a, what should I plug in as my ω to find the period of the planet's rotation? For part b, how do I set it up to find tangential v?
  2. jcsd
  3. Mar 23, 2012 #2
    Hm, a strange lack of response. Is my question worded weirdly? I guess I'll have to solve this problem by myself.
  4. Mar 23, 2012 #3


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    Staff: Mentor

    Perhaps you could detail the work you did to find the results that you've stated in your first post. To me they don't appear to be correct. In fact they don't agree very well with the stipulation that ωv = 5ωp (where v → vehicle; p → planet).
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