8. The mass density of a certain planet has spherical symmetry but varies in such a way that the mass inside every spherical surface with center at the center of the planet is proportional to the radius of the surface. If r is the distance from the center of the planet to a point mass inside the planet, the gravitational force on the mass is: (A) not dependent on r (B) proportional to r (C) proportional to r² (D) proportional to 1/r (E) proportional to 1/r²

11. A small metal sphere is suspended from the conducting cover of a conducting metal ice bucket by a non-conducting thread. The sphere is given a negative charge before the cover is placed on the bucket. The bucket is tilted by means of a non-conducting material so that the charged sphere touches the inside of the bucket. Which statement is correct? (A) The negative charge remains on the metal sphere. (B) The negative charge spreads over the outside surface of the bucket and cover. (C) The negative charge spreads over the inside surface of the bucket and cover. (D) The negative charge spreads equally over the inside and outside surfaces of the bucket and cover. (E) The negative charge spreads equally over the sphere and the inside and outside surfaces of the bucket and cover.

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