If an object weighs 39.2 N on Earth what is its mass?

Well, darling, weight is the force of gravity acting on an object, and mass is the amount of matter in an object. Since weight is given in Newtons, we can use the formula weight = mass x acceleration due to gravity (9.81 m/s^2) to find the mass. So, 39.2 N = mass x 9.81 m/s^2, giving us a mass of approximately 4 kg. Voilà!