TA: Tomoyuki Nakayama Monday, March 29 th , 2010 PHY 2048: Physic 1, Discussion Section 3081 Quiz 8 (Homework Set # 11) Name: UFID: Formula sheets are not allowed. Calculators are allowed. Do not store equations in your calculator. You need to show all of your work for full credit. ________________________________________________________________________________ Assume a planet is a uniform sphere of radius R and mass M that (somehow) has a narrow radial tunnel through its center. Also assume we can position an apple of mass m anywhere along the tunnel or outside the sphere. Let F R be the magnitude of the gravitational force on the apple when it is located at the planet’s surface. a) How far from the surface is there a point where the magnitude of the gravitational force on the apple is (1/3) F R if we move the apple away from the planet. Let r be the position of the apple measured from the center of the sphere. Since r>R, the sphere exerts force on the apple as if all of its mass were concentrated at the center. We have
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