1. a The acceleration of free fall at the surface of a planet is g, and the radius of the planet is R. Deduce that the period of a satellite in a very low orbit is given by T=2πgR .
2. b Given that g=4.5 m s−2 and R=3.4×106 m, deduce that the orbital period of the low orbit is about 91 minutes.
3. c A spacecraft in orbit around this planet has a period of 140 minutes. Deduce the height of the spacecraft from the surface of the planet.