Use acceleration due to gravity, 10.67 meters/second^2. Then we need to find how fast we need to go to escape the planet, which is the difficult part. Escape velocity is calculated by the equation, sq rt. (2GM/R) where G is gravitational constant (6.67E-11) M is mass of object (planet), and R is radius of object (again, the planet). Input Uranus, work it out, and according to nnsdc.gsfc.nasa.gov, it is about 21.1 km/s That's fast...