How will you ‘weigh the sun’, that is estimate its mass? The mean orbital radius of the earth around the sun is 1.5 × 108 km. | Learn NCERT solution | Education portal Class 11 Physics | Study online Unit-8 Gravitation



Q.13:- How will you ‘weigh the sun’, that is estimate its mass? The mean orbital radius of the earth around the sun is 1.5 × 108 km.

 

Answer:-



Orbital radius of the Earth around the Sun, r = 1.5 × 1011 m
Time taken by the Earth to complete one revolution around the Sun,
T = 1 year = 365.25 days
= 365.25 × 24 × 60 × 60 s
Universal gravitational constant, G = 6.67 × 10–11 Nm2 kg–2
Thus, mass of the Sun can be calculated using the relation,
M = 4π2r3 / GT2
= 4 × 3.142 × (1.5 × 1011)3 / [ 6.67 × 10-11 × (365.25 × 24 × 60 × 60)2]
= 2 × 1030 kg
Hence, the mass of the Sun is 2 × 1030 kg.