Ganymede is a moon of Jupiter (mass = 1.90 x 1027 kg). It orbits Jupiter in a circle of radius 1.07 x 109 m. What is Ganymede's period in hours)?

Answer 1

A variant of Kepler's third law says:

where G = 6.674 x 10^-11

So T = (2π/√( 6.674 x 10^-11•1.90 x 10²⁷)(1.07 x 10⁹)^3/2

T = 6.283/√(1,26 x 10¹⁷)(3.5 x 10¹³)

T = 617569 seconds

To convert to hours, divide by 3600 (there are 3600 seconds in an hour)

T = 172 hours