In 1610 Galileo made a telescope and used it to study the planet Jupiter. He discovered four moons. One of them was Ganymede. The mean radius of the orbit of Ganymede around Jupiter is 10.7 × 108m and the period of the orbit is 7.16 days. i) Determine the mass of Jupiter.

Respuesta :

Answer: [tex]1.893(10)^{27}kg [/tex]

Explanation:

This problem can be solved by the Third Kepler’s Law of Planetary motion, which states:

“The square of the orbital period of a planet is proportional to the cube of the semi-major axis (size) of its orbit”.

In other words, this law stablishes a relation between the orbital period [tex]T[/tex] of a body (moon, planet, satellite) orbiting a greater body in space with the size [tex]a[/tex] of its orbit.

This Law is originally expressed as follows:

[tex]T^{2}=\frac{4\pi^{2}}{GM}a^{3}[/tex]    (1)

Where;

[tex]T=7.16days=618624s[/tex]  is the period of the orbit Ganymede describes around Jupiter

[tex]G[/tex] is the Gravitational Constant and its value is [tex]6.674(10)^{-11}\frac{m^{3}}{kgs^{2}}[/tex]

[tex]M[/tex] is the mass of Jupiter  (the value we need to find)

[tex]a=10.7(10)^{8}m[/tex]  is the semimajor axis of the orbit Ganymede describes around Jupiter (assuming it is a circular orbit, the semimajor axis is equal to the radius of the orbit)

If we want to find [tex]M[/tex], we have to express equation (1) as written below and substitute all the values:

[tex]M=\frac{4\pi^{2}}{GT^{2}}a^{3}[/tex]    (2)

[tex]M=\frac{4\pi^{2}}{(6.674(10)^{-11}\frac{m^{3}}{kgs^{2}})(618624s)^{2}}(10.7(10)^{8}m)^{3}[/tex]    (3)

Finally:

[tex]M=1.8934(10)^{27}kg[/tex]   This is the mass of Jupiter