If an astronaut could stand on Ceres, what percentage of Earths gravity would she/he experience?
We’ll first give the general solution and then apply it to Ceres. Assume first that all planetary bodies are made of the same material. The volume of a planet is proportional to the cube of the radius and hence the mass [equal to the density times the volume] is also proportional to the cube of the radius. Surface gravity is proportional to the mass and inversely as the radius squared. Multiplying our formula for mass and surface gravity together we get that surface gravity increases as the radius of the planet. So if Ceres [ a little under 500 km radius] were made of the same material as Earth [ a little over 6000 km radius] then the astronaut would weigh [experience a force of gravity of] about 1/12 of that on Earth. However, Ceres has a density of about 1/3 of that of Earth and there the astronaut would weigh about 3% of his Earth-bound weight. Problem for reader: The radius of Vesta is close to half that of Ceres and its density close to twice that of Ceres. Follow the example abov
