The little prince ( the main charcter of the novel written by Antione de saint-Exupery) lives on the spherical planet named `B-612`, the density of which is `5200kg//m^(3)`. The little prince noticed that if he quickens his pace, he feels himself ligheter. when he reached the speed of `2m//s` he became weightless, and began to orbit about the planet as a satellite. what is escape speed on the surface of planet?