3.

The small spherical planet called "Glob" has a mass of 6.5010¹⁸ kg and a radius of 6.4010⁴ m. An astronaut on the surface of Glob throws a rock straight up. The rock reaches a maximum height of 1.6010³ m above the surface of the planet before it falls back down.

3a

What was the initial speed of the rock (in m/s)as it left the astronaut's hand? (Glob has no atmosphere, so no energy is lost to air friction.) G=6.6710¹¹G=6.6710¹¹Nm²/kg².

3b

A 27.0 kg satellite is in a circular orbit with a radius of 160000 m around the planet Glob.

Calculate the speed of the satellite (in m/s).