Density of the sun as a white dwarf.

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SUMMARY

The discussion centers on calculating the density of the sun as a white dwarf, which will occur in approximately 5 billion years. The mass of the sun is established as 1.99 x 1030 kg, and the diameter at that stage is approximately 15,000 km. The correct density calculation involves using the formula D = m/v, with the volume calculated from the radius of 7.5 x 108 cm. The final density, after correcting for errors in the radius and volume calculations, is determined to be 6.338 x 1023 g/cm3.

PREREQUISITES
  • Understanding of the density formula D = m/v
  • Knowledge of volume calculation for a sphere: V = 4/3πr3
  • Familiarity with unit conversions, specifically from kilograms to grams
  • Basic grasp of scientific notation and exponent manipulation
NEXT STEPS
  • Review the principles of stellar evolution and the lifecycle of stars
  • Study the properties and characteristics of white dwarfs
  • Learn about unit conversions in physics, particularly mass and volume
  • Explore advanced density calculations in astrophysics
USEFUL FOR

Astronomy students, astrophysicists, and anyone interested in stellar evolution and the physical properties of celestial bodies.

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Homework Statement



In about 5 billion years, at the end of its lifetime, our sun will end up as a white dwarf, having about the same mass as it does now, but reduced to about 15,000 km in diameter.What will be its density at that stage?

g/cm^3

Homework Equations



D=m/v
4/3(3.14)r^3

The Attempt at a Solution



Sun's mass is Sun's mass is = 1.99 x 10^30 kg
kg to g = 1.99 x 10^33
v = 7500 km to 750,000,000 centimeter

D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^33)^3 = 1.12 x 10^54 ?

Is this correct? I have been getting it wrong each time I input the answer
 
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Look at what you put for the radius in your equation.
 
D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^9)^3 = 2.09 x 10^11?
 
You're off by a factor of 10 somewhere. Careful of your exponents.
 
D = 1.99 x 10^33 / (4/3)(3.14)(7.5 x 10^8)^3 = 6.338 x 10^23
Seems to be wrong.
 
Your equation is correct. Take it one step at a time.
 
negitron said:
Take it one step at a time.

Agreed. What is the volume? Then take the ratio mass/volume.
 

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