A planet of radius has the same mass density as Earth

PHYSICS · Single correct · AP · Physics C: Mechanics · Force and Translational Dynamics · Force and Translational Dynamics

Problem

A planet of radius R=110×(radius of Earth)R = \frac{1}{10} \times (\text{radius of Earth}) has the same mass density as Earth. Scientists dig a well of depth R5\frac{R}{5} on it and lower a wire of the same length and a linear mass density 10−3 kg m−110^{-3} \text{ kg m}^{-1} into it. If the wire is not touching anywhere, the force applied at the top of the wire by a person holding it in place is (take the radius of Earth = 6×106 m6 \times 10^6 \text{ m} and the acceleration due to gravity on Earth is 10 ms−210 \text{ ms}^{-2} ) (1) 96 N (2) 108 N (3) 120 N (4) 150 N

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