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Gravitational pull of moon

  1. Dec 1, 2006 #1
    A 1-kg mass at the earth's surface is gravitationally attracted to earth with a force of 9.8 N. Calculate the force of gravity with which the 1-kg mass on earth is attracted to the moon. (The moon's mass is 7.4 x 10^22 kg)

    Would this be setup correctly?


    F=(G me mb)/r^2

    F=(6.67*10^(-11))(7.4*10^22 kg)(5.98*10^24 kg)/(3.84*10^20)^2=1.99*10^20 N

    F=ma
    F=(1kg)(1.99*10^20 N)=1.99*10^20 N
     
  2. jcsd
  3. Dec 1, 2006 #2

    Doc Al

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    Staff: Mentor

    Do you really think that your answer makes sense? That an object right on the surface of the huge earth feels a force of about 10 N towards the earth, but also feels a force a gazillion times bigger pulling it to the smaller and more distant moon??? :yuck:

    Hint: You need the gravitational force between Object and Moon, so the only masses involved would be that of the object and the moon.
     
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