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Homework Help: Rotational Motion of the sun

  1. Oct 29, 2006 #1
    The Sun subtends an angle of about 0.5 degrees to us on the Earth, 150 million km away. What is the radius of the Sun?


    (2pi rad/360 degrees)0.5 degrees=2pi(150,000,000 km)

    This should be simple, but the answer I get seems to not sound right at all

    Have i set this up correctly?
  2. jcsd
  3. Oct 29, 2006 #2


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    Why is the title of this thread rotational motion? This is something else. Your equation is correct for finding the diameter of the sun, and you do need to convert to radians as you have done. If I may change the letter for diameter to D, you have

    theta = D/R

    where R is the distance from the sun to the earth. Solve this for D and try your calculation again. Then remember to find the radius of the sun from D.
  4. Oct 31, 2006 #3
    theta =D/R

    (2pi rad/360°)(0.5°)=D/(150,000,000 km)

    D=(1,308,997 km)

    R=(1,308,997 km)/2= 654,499 km

  5. Nov 1, 2006 #4


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    Much better
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