Let us consider that our galaxy consists of 2.5 xx 10^11 stars each of one solar mass. How long will a star at a distance of 50,000 ly from thegalactic centre take to complete one revolution ? Take the diameter of the milky way to be 10^5 ly .G = 6.67 xx 10^(-11) Nm^2 Kg^2

Let us consider that our galaxy consists of 2.5 xx 10^11 stars each of

1.	Let us consider that our galaxy consists of 2.5 xx 10^11 stars each of one solar mass. How long will a star at a distance of 50,000 ly from thegalactic centre take to complete one revolution ? Take the diameter of the milky way to be 10^5 ly .G = 6.67 xx 10^(-11) Nm^2 Kg^2
Answer» SOLUTION :`M = 2.5 XX 10^11 `solar mass ` = 2.5 xx 10^11 xx (2 xx 10^30 )kg= 5.0 xx 10^41 kg ` We know that `M = (4pi^2 R^3)/(GT^2) ` ` r = 50,000ly = 50,000 xx 9.46 xx 10^15 m = 4.73 xx 10^20m` ` T = ((4pi^2 r^3)/(GM))^(1//2) = [(4 xx (22//7)^2 xx (4.73 xx 10^20)^3)/((6.67 xx 10^(-11)) xx (5.0 xx 10^41))]^(1/2) = 1.12 xx 10^16 s `