As an astronaut, you observe a small planet to be spherical. After landing on the planet, you set off, always walking straight ahead, and find yourself back at your spacecraft from the opposite side after completing a lap of 22.5 km. You hold a hammer and a falcon feather at a height of 1.30 m, release them, and observe that they fall together to the surface in 25.1 s. Determine the mass of the planet.

 

Calculate the mass of the planet in kg, and express it as  a×10^b