Gravitation

The planet Mars has two

moons, phobos and delmos. (i) phobos has

a period 7 hours, 39 minutes and an orbital

radius of 9.4 ×10³km. Calculate the mass

of mars. (ii) Assume that earth and mars

move in circular orbits around the sun,

with the martian orbit being 1.52 times

the orbital radius of the earth. What is

the length of the martian year in days ?