If the mass of the earth and all objects on it were suddenly doubled, but the size remained the same, the acceleration due to gravity at the surface would become
a) 1/2 of what it now is.
b) 2 times what it now is.
c) 1/4 of what it now is.
d) the same as it now is.
e) 4 times what it now is.

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The answer is B) 2 times what it is now.

change tension

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.