Let’s say there are 5000 galaxies within a 2.5 Mpc diameter spherical volume of
ID: 119880 • Letter: L
Question
Let’s say there are 5000 galaxies within a 2.5 Mpc diameter spherical volume of the Coma Cluster and that there are 10000 galaxies within a 60 Mpc diameter spherical volume comprising the Bootes Void. What is the ratio of the galaxy density of the cluster and the galaxy density in the void? Calculate the ratio of the densities of iron and air (look these up) and compare to the result for the cluster/void density ratio. By what factor is the iron/air density ratio bigger or smaller than the cluster/void density ratio?
Remember, a number density is just the number of something divided by the volume that something fills. You are given info to determine TWO distinct number densities, one in a Void and one in a cluster. You will need to look up the mass densities of iron and air; be sure to report those (with units!) in your answer.
Remember, a number density is just the number of something divided by the volume that something fills. You are given info to determine TWO distinct number densities, one in a Void and one in a cluster. You will need to look up the mass densities of iron and air; be sure to report those (with units!) in your answer.
Explanation / Answer
volume of sphere= 4 pi (radius)3/3
Galaxy density of cluster / Galaxy density of void= (number of galaxy/ volume of cluster) / (number of galaxy / volume of void)
= [5000/ (4 pi (1.25)3 /3)] / [(10000/ (4 pi (30)3 /3)]
= 6912
Density of Iron=7870 kg/m3
Density of air= 1.225 kg/m3
Ratio= 7870/ 1.225
=314800/49
=6424.4897
The ratio of density of iron and air is smaller then the ratio of cluster void density
If you multiply 1.0758831 with the ratio of density of iron and air , you will get cluster void density ratio.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.