1) The 25 kg Rover X23K landed on a strange planet. It started traveling in one direction around this planet's surface along its equator until it got back to the same location. The Rover had a constant speed of 3.6 km/h and it completed the trip in 24 hours. The camera of the rover recorded a boulder falling off a 12.5 m high cliff. It took 5.0 seconds for the boulder to hit the ground. a) What is the gravitational field at the surface of this planet? [4 marks] b) What is the mass of this planet? [4 marks] c) What is the mechanical energy of the rover if an infinite distance from the center of the planet is used as a zero potential energy? [2 marks]