Question

The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 10⁷ K, and its outer surface at a temperature of about 6000 K. At these high temperatures, no substance remains in a solid or liquid phase. In what range do you expect the mass density of the Sun to be, in the range of densities of solids and liquids or gases ? Check if your guess is correct from the following data : mass of the Sun = 2.0 ×10³⁰ kg, radius of the Sun = 7.0 × 10⁸m.

Answer 1

Given, the mass of the Sun is 2.0× 10 30  kg and the radius of the Sun is 7.0× 10 −8  m .

Let r be the radius of the sun

The volume of the Sun is given as,

V= 4 3 π r 3

Substitute the given value in the above expression.

V= 4 3 π ( 7.0× 10 8  m ) 3 =1.44× 10 27   m 3

The density of the Sun is,

ρ= M V

Substitute the given value in the above expression.

ρ= 2.0× 10 30  kg 1.44× 10 27   m 3 =1.38× 10 3   kg/ m 3 ≅1.4× 10 3   kg/ m 3

The value of density lies in the range of densities of the solid and liquid.

The density of gas is very low. The density of sun is high because of the gravitational force of attraction between the outer and inner layer of the sun.