On July 4, 2005, the NASA space-craft Deep Impact fired a projectile to the surface of Comet Tempel 1. This comet is approx 9.0 km across. Observations of surface debris liberated by the impact showed that dust having a speed as low as 1.0 m/s was capable to escape the comet.
i) Supposing a spherical shape, determine the mass of the comet? (The escape speed for an object at the surface of Earth is 11.2 km/s).
ii) Determine how far from the comet's center will this debris be when it has lost 70 percent of its initial kinetic energy at the surface?