The radius of Planet C is close to half that of Earth, and both have the same average density. Compared to Earth’s gravitational acceleration at the surface, approximately what will Planet C’s gravity be at its surface?

Is it 1/4 g because of the inverse square law?


closed as off-topic by John Rennie, user36790, user108787, ACuriousMind, Jon Custer Sep 25 '16 at 21:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – John Rennie, Community, Community, ACuriousMind, Jon Custer
If this question can be reworded to fit the rules in the help center, please edit the question.


You are assuming the mass is the same, and focusing on the inverse square dependence on radius. But it's not given that the mass is the same, it is given that the density is the same. So calculate the mass ratio, and include that mass difference along with the radius difference.


Not the answer you're looking for? Browse other questions tagged or ask your own question.