Question

In another solar system a planet has twice the earth's mass and three times the earth's radius. your weight on this planet is ________ times your earth-weight. assume that the masses of the earth and of the other planet are uniformly distributed. (a) 0.667 (b) 2.000 (c) 0.111 (d) 0.444 (e) 0.222

Answer 1

g = - GM/r^2 so we have:

-G * M / r^2 and -G * 2 * M / (r * 3)^2

Cleaning up the equation since we don’t need the negatives or G since they are constant in both equations:

M / r^2 and 2 * M / (r * 3)^2

We’ll set M to 1 and r to 1 so we get:

1 / 1^2 and 2 * 1(1 * 3)^2

1 and 2 / 3^2 would be equivalent to 1 and 2/9.

Therefore, for every 1 kg on Earth, you would weigh 0.2222 kg on the new planet.