1. The problem statement, all variables and given/known data The weight of an object of mass 1kg at the surface of Mars is about 4N. The radius of Mars is about half the radius of Earth. Estimate the ratio: mass of Mars/Mass of Earth 2. Relevant equations 3. The attempt at a solution The answer is 0.1 but I don’t see where that comes from? 1kg would be 10N on Earth but 4/10 is 0.4 not 0.1? I’m assuming the radius is important but I don’t know how.