# Io, One of the Satellites of Jupiter, Has an Orbital Period of 1.769 Days and the Radius of the Orbit is 4.22 × 108 M. Show that the Mass of Jupiter is About One-thousandth that of the Sun. - Physics

Io, one of the satellites of Jupiter, has an orbital period of 1.769 days and the radius of the orbit is 4.22 × 108 m. Show that the mass of Jupiter is about one-thousandth that of the sun.

#### Solution 1

Orbital period of I_0, T_"Io" = 1.769 days = 1.769 xx 24 xx 60 xx 60 s

Orbital radius of I_0, R_"Io" = 4.22 xx 10^8 m

Satellite I_0 is revolving around the Jupiter

Mass of the latter is given by the relation:

M_J = (4pi^2R_(+-)^3)/(GT_"Io"^2)  ....(i)

Where

M_J = Mass of Jupiter

G = Universal gravitational constant

Orbital period of the earth

T_e = 365.25 days  = 365.25 xx 24 xx 60xx 60s

R_e = 1 AU = 1.496 xx 10^(11) m

Mass of Sun is given as

M_s = (4pi^2R_e^3)/(GT_e^2) .. (ii)

:. M_s/M_J = (4pi^2R_e^3)/(GT_e^2) xx (GT_(Io)^2)/(4pi^2R_"Io"^3) = (R_e^3)/R_"Io"^3xx(T_"Io"^2)/(T_e^2)

=((1.769xx24xx60xx60)/(365.25xx24xx60xx60))^2xx((1.496xx10^(11))/(4.22xx10^8))

=1045.04

:.M_s/M_J ~ 1000

M_s "~" 1000xx M_J

Hence, it can be inferred that the mass of Jupiter is about one-thousandth that of the Sun.

#### Solution 2

For a satellite of Jupiter, orbital period, T1 = 1.769 days = 1.769 x 24 x 60 x 60 s Radius of the orbit of satellite, r1 = 4.22 x 108 m

Mass of Jupiter, M_1 is given by M_1  = (4pi^2r_1^3)/(GT_1^2) = (4pi^2xx(4.22xx10^8)^2)/(Gxx(1.769xx24xx60xx60)^2)

We know that the orbital period of earth around the sun

T = 1 year  = 365.25 x 24 x 60 x 60 s

orbital radius r = 1 A.U = 1.496 xx 10^(11) m

Mass of sun is given by M = (4pi^2r^3)/(GT^2) = (4pi^2xx(1.496xx10^11)^3)/(Gxx(1.769 xx 24 xx 60 xx 60)^2)  ...(ii)

Dividing equation ii by i we get

M/M_1 = (4pi^2xx(1.496xx10^(11))^3)/(Gxx(1.769xx24xx60xx60)^2)xx (Gxx(1.769xx24xx60xx60)^2)/(4pi^2xx(4.22xx10^8)^3) = 1046

or  M_1/M = 1/1046 = 1/1000 => M_1 = 1/1000 M

Proved

Concept: Acceleration Due to Gravity and Its Variation with Altitude and Depth
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#### APPEARS IN

NCERT Class 11 Physics
Chapter 8 Gravitation
Exercises | Q 4 | Page 201