Universe: Stars And Galaxies
Universe: Stars And Galaxies
6th Edition
ISBN: 9781319115098
Author: Roger Freedman, Robert Geller, William J. Kaufmann
Publisher: W. H. Freeman
bartleby

Concept explainers

Question
Book Icon
Chapter 25, Problem 41Q
To determine

(a)

The critical density of matter in the universe.

Expert Solution
Check Mark

Answer to Problem 41Q

The critical density of matter in the universe is 4.699×1038kg/m3.

Explanation of Solution

Given:

The Hubble constant is, H1=50km/sMpc.

Formula used:

The critical density of matter in the universe is given by,

ρc=3H28πG

Calculation:

The gravitational constant is, G=6.67×1011m3/kgs2

The critical density of matter in the universe is calculated as,

ρc=3H28πG=3 ( 50 kmMpc/ sMpc )28π( 6.67× 10 11 m 3 / kg s 2 )=3 ( 50 km/ sMpc )2 ( 1Mpc 3.0856× 10 13 Mkm )28π( 6.67× 10 11 m 3 / kg s 2 )=3 ( 50 km/ sMpc )2 ( 1Mpc 3.0856× 10 13 Mkm( 10 6 km 1Mkm ) )2( 167.63 m 3 / kg s 2 )

Solve further,

ρc=3 ( 16.20× 10 19 s 1 )2( 167.63 m 3 / kg s 2 )=787.738× 10 38s 2( 167.63 m 3 / kg s 2 )=4.699×1038kg/m3

Conclusion:

The critical density of matter in the universe is 4.699×1038kg/m3.

To determine

(b)

The critical density of matter in the universe.

Expert Solution
Check Mark

Answer to Problem 41Q

The critical density of matter in the universe is 6.266×1038kg/m3.

Explanation of Solution

Given:

The Hubble constant is, H1=100km/sMpc.

Calculation:

The critical density of matter in the universe is calculated as,

ρc=3H28πG=3 ( 100 kmMpc/ sMpc )28π( 6.67× 10 11 m 3 / kg s 2 )=3 ( 100 km/ sMpc )2 ( 1Mpc 3.0856× 10 13 Mkm )28π( 6.67× 10 11 m 3 / kg s 2 )=3 ( 100 km/ sMpc )2 ( 1Mpc 3.0856× 10 13 Mkm( 10 6 km 1Mkm ) )2( 167.63 m 3 / kg s 2 )

Solve further,

ρc=3 ( 32.40× 10 19 s 1 )2( 167.63 m 3 / kg s 2 )=1050.317× 10 38s 2( 167.63 m 3 / kg s 2 )=6.266×1038kg/m3

Conclusion:

The critical density of matter in the universe is 6.266×1038kg/m3.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
The matter density in the Universe today is ?m=2.7×10−27kgm−3. What would be the value of the density parameter, Ω0, if the Hubble constant had the value H0  = 38 km/s/Mpc?
The mass of the neutrino plays an important role in the universe. Suppose the mass of two neutrinos in the universe is 4.8×10-³5 kg and the current Hubble’s constant is 72 km/s/Mpc. The critical density of the universe is five times the average density of the universe. Estimate the number of neutrons present per cubic meter in the universe. (a) 2.1×10⁹ (b) 4.1×10² (c) 1.1x10° (d) 8.1×107
What would be your estimate for the age of the universe if you measured Hubbleʹs constant to be 33 km/s/Mly? You can assume that the expansion rate has remained unchanged during the history of the universe.
Knowledge Booster
Background pattern image
Physics
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
Text book image
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
Text book image
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
Text book image
Modern Physics
Physics
ISBN:9781111794378
Author:Raymond A. Serway, Clement J. Moses, Curt A. Moyer
Publisher:Cengage Learning
Text book image
Principles of Physics: A Calculus-Based Text
Physics
ISBN:9781133104261
Author:Raymond A. Serway, John W. Jewett
Publisher:Cengage Learning