Planet Zero has a mass of 4.5 × 10^23 kg and a radius of 1.9 × 10^6 m. A space probe is launched vertically from the surface of Zero with an initial speed of 5 km/s.
What is the speed of the probe when it is 2.9 × 106 m from Zero's center? The gravitational constant is 6.6726 × 10^-11 N· m2/kg2.
Answer in units of km/s.