Question: The mean diameters of X and Y, two planets in the same solar system, are 6.4 x 103 km and 1.2 x 104 km, respectively. The mass of X is 0.25 times the mass of Y. The value of g on Y is 8.8 m/s2. The mass of Y is 4.750 x 1024 kg. What is the escape speed on X?