1. The problem statement, all variables and given/known data Moon's gravity is 5.31ft/sec^2 An object has the weight of 3.5 lb-f on the moon. What is its lb-m What is the lb-m and lb-f on Mars with gravity of 12.1 ft/sec^2. 2. Relevant equations w=mg=mg/gc gc= gravitational constant----> 32lbm*ft/sec^2 for earth 3. The attempt at a solution So I understand mass is the same everywhere. Also lb-m and lb-f are the same numerically on earth but not on other planets? Im just really confused with imperial units because i dont understand when to use or not use the gc.