{"knowledge_schema": {"broad_category": "Astronomy \u2192 Planetary Science \u2192 Density of Planets", "refinement": "This problem involves calculating the density of different planets based on their mass and radius, which are key factors in determining a planet's density.", "specific_scope": "The task is to compare the densities of four different hypothetical planets using the formula for density (density = mass/volume) and the relationship between volume and radius.", "goal": "Identify which of the given planets has the lowest density by calculating and comparing their densities."}, "summary": "This problem is centered around the concept of planetary density, which is determined by the mass and volume of a planet. To find the density, we use the formula density = mass/volume, where volume can be calculated from the radius. The task requires comparing the densities of four hypothetical planets with different masses and radii. The goal is to determine which planet has the lowest density, and the answer is found to be the planet with 2 Earth masses and a radius of 1.5 times Earth's radius."}