Question

An unknown planet has two spherical moons in circular orbits.

The following table summarizes the hypothetical data about the moons.

Both moons have low axial spin rates.

G = 6.67 10^-11 Nm^2/kg^2

	Mass	Radius	Orbital radius	Orbital period
Moon A	8.0 × 10^20 kg		2.0 × 10^8 m	4.0 × 10^6 s
Moon B	3.0 × 10^20 kg	2.0 × 10^5 m	3.0 × 10^8 m

1)

What is (in m/s^2) the acceleration due to gravity at the surface of Moon B

(4pts)

Question 1 - What is (in m/s^2) the acceleration due to gravity at the surface of Moon B

Enter your answer

2)

What is the ratio of the mass of the planet to the mass of moon A, i.e. mplanet/mmoon A?

(4pts)

Question 2 - What is the ratio of the mass of the planet to the mass of moon A, i.e. mplanet/mmoon A?

Enter your answer

3)

What is the ratio of the period of moon B to that of moon A (i.e. what is TB/TA)?

(4pts)

Question 3 - What is the ratio of the period of moon B to that of moon A (i.e. what is TB/TA)?

Enter your answer

4)

If the acceleration due to gravity at the surface of A is twice that at the surface of B, calculate the ratio of both radii (RA/RB).

(4pts)

Question 4 - If the acceleration due to gravity at the surface of A is twice that at the surface of B, calculate the ratio of both radii (RA/RB).

Enter your answer

SP

5)

How much energy is required to take a satellite of mass m from a circular orbit of radius r to one of radius 3r around a planet of mass M.

(4pts)

Question 5 - How much energy is required to take a satellite of mass m from a circular orbit of radius r to one of radius 3r around a planet of mass M.

Select 2GMm/3r as your answer	2GMm/3r
Select GMm/2r as your answer	GMm/2r
Select GMm/3r as your answer	GMm/3r
Select GMm/6r as your answer	GMm/6r
Select 3GMm/r as your answer	3GMm/r

Answer 1