The force of attraction due to a hollow spherical shell of uniform density, on a point mass situated inside it, is

A rocket is fired ‘vertically’ from the surface of mars with a speed of 2 km s−1s−1 . If 20 percent of its initial energy is lost due to Martian atmospheric resistance, how far will the rocket go from the surface of mars before returning to it? Mass of mars = 6.4 ×× 10231023 kg; radius of mars = 3395 km; G = 6.67 ×× 10−1110−11 N m2m2 kg−2−2.