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Homework Help: Help with Gravitation questions

  1. Apr 29, 2004 #1
    The first one just confuses me because of the word in the brackets.

    1. A 70kg boy stands 1.0 m away from a 60 kg girl. Find the force of attraction (gravitational) between them.

    For this would I just sub the values into F=Gm1m2/r^2?

    The second question is giving me a lot of problems.

    2. How fast would the earth (r=6400km) have to be spinning befor a 100kg person would exert no force on a scale at the equator? Assume the earth is a perfect sphere and it's mass is 6.0 * 10^24 kg.

    For this I took F=ma and subbed in a=4 (pi)^2 r / T^2. Then I made F=0 and solved for T, but my answer gave me a period of 44 hours. This can't be write since it would have to be spinning faster than 24 hours. Please help.
     
  2. jcsd
  3. Apr 29, 2004 #2

    Doc Al

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    Staff: Mentor

    It's just a joke--gravitational attraction versus the non-physics kind. :wink:
    Right.

    Check out this thread:
    https://www.physicsforums.com/showthread.php?t=17606
     
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