CONCEPTUAL PHYSICAL SCI.(LOOSE)-PACKAGE
6th Edition
ISBN: 9780134687568
Author: Hewitt
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 28, Problem 48E
No galaxy that has been found so far is less than 25% helium. If not from the stars, where did this helium come from?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Pretend that galaxies are spaced evenly, 7.0 Mpc apart, and the average mass of a galaxy is 1.0 ✕ 1011 M. What is the average density (in kg/m3) of matter in the universe? (Note: The volume of a sphere is 4/3pieR^3 and the mass of the sun is 2.0 ✕ 1030 kg.)
______ kg/m^3
Which model universe does this density value support?
A: open
B: flat
C: closed
A galaxy's rotation curve is a measure of the orbital speed of stars as a function of distance
from the galaxy's centre. The fact that rotation curves are primarily flat at large galactocen-
tric distances (vrot(r) ~ constant) is the most common example of why astronomer's believe
dark matter exists. Let's work out why!
Assuming that each star in a given galaxy has a circular orbit, we know that the accelera-
tion due to gravity felt by each star is due to the mass enclosed within its orbital radius r and
equal to v?/r. Here, ve is the circular orbit velocity of the star. (a) Show that the expected
relationship between ve and r due to the stellar halo (p(r) xr-3.5) does not produce a flat
rotation curve. (b) Show that a p(r) ∞ r¯² density profile successfully produces a flat ro-
tation curve and must therefore be the general profile that dark matter follows in our galaxy.
Pretend that galaxies are spaced evenly, 2.0 Mpc apart, and the average mass of a galaxy is 1.0 x 1011 Mo: What is the average density (in kg/m3)
of matter in the universe? (ote: The volume of a sphere is
, and the mass of the sun is 2.0 x 1030 kg.)
kg/m3
Chapter 28 Solutions
CONCEPTUAL PHYSICAL SCI.(LOOSE)-PACKAGE
Ch. 28 - Is the universe in space or is space in the...Ch. 28 - What is a Cepheid?Ch. 28 - Prob. 3RCQCh. 28 - What is the approximate age of the universe?Ch. 28 - the average temperature of the universe today is...Ch. 28 - According to cosmic inflation theory, how long did...Ch. 28 - At what point did the universes temperature even...Ch. 28 - What did inflation do to the quantum fluctuations...Ch. 28 - Prob. 9RCQCh. 28 - How many dimensions are there in spacetime?
Ch. 28 - Prob. 11RCQCh. 28 - Car an accelerated frame of reference be...Ch. 28 - You release a ball while standing on the floor of...Ch. 28 - Prob. 14RCQCh. 28 - What happens to starlight as it passes close to...Ch. 28 - If you walk at 1 km/h down the aisle toward the...Ch. 28 - In the preceding question, is your approximate...Ch. 28 - Within a spaceship moving at 99% the speed of...Ch. 28 - Why is the essence of a coffee table best captured...Ch. 28 - Does it necessarily take a minimum of 25,000 years...Ch. 28 - Prob. 21RCQCh. 28 - If we cant see dark matter, how do we know it is...Ch. 28 - Is dark matter found mostly within a galaxy or...Ch. 28 - The closer a planet is to the Sun, the faster it...Ch. 28 - In a huge cloud of ordinary matter and dark...Ch. 28 - Prob. 26RCQCh. 28 - What was Einsteins cosmological constant?Ch. 28 - What did Einstein refer to as the greatest blunder...Ch. 28 - According to recent evidence, how long ago did the...Ch. 28 - What does WMAP stand for?Ch. 28 - The Fate of the Universe 31. What is probably the...Ch. 28 - Which is more abundant: dark matter or ordinary...Ch. 28 - According to the heat death scenario, about how...Ch. 28 - What does the Big Rip scenario assume about dark...Ch. 28 - What scenario for the fate of the universe...Ch. 28 - Rank the following in order of increasing...Ch. 28 - Rank the following in order of increasing...Ch. 28 - Rank the following in order of longest ago to most...Ch. 28 - Rank the following in order of increasing...Ch. 28 - When was most of the helium in the universe...Ch. 28 - What does the expansion of space do to light...Ch. 28 - A police officer pulls you over for speeding. He...Ch. 28 - If the initial universe had remained hotter for a...Ch. 28 - Prob. 47ECh. 28 - No galaxy that has been found so far is less than...Ch. 28 - Are astronomers able to point their telescopes in...Ch. 28 - A helium balloon here on Earth pops, releasing...Ch. 28 - Astronomers tell us that the average temperature...Ch. 28 - The average temperature of the universe right now...Ch. 28 - What are three lines of evidence supporting cosmic...Ch. 28 - What if there were symmetry to cosmic background...Ch. 28 - Is cosmic inflation a cause or an effect? How...Ch. 28 - Prob. 56ECh. 28 - If gravity is not a force, then what is it?Ch. 28 - You toss a tennis ball up and down in front of you...Ch. 28 - You toss a tennis ball up and down in front of you...Ch. 28 - Prob. 60ECh. 28 - Where does a clock run slower: at the front end or...Ch. 28 - Prob. 62ECh. 28 - An astronaut is provided a gravity when the ships...Ch. 28 - Being ultra-sensitive, should a person who wants...Ch. 28 - If you stand in the street and shine a beam of...Ch. 28 - A man leaves his identical twin brother behind to...Ch. 28 - Why does the gravitational attraction between the...Ch. 28 - When do clocks move slowest on Mercury?Ch. 28 - Prob. 69ECh. 28 - Prob. 70ECh. 28 - When you drive down the highway, you are moving...Ch. 28 - Astronomers view light coming from distant...Ch. 28 - Inside the moving compartment of Figure 28.18,...Ch. 28 - Prob. 74ECh. 28 - Time is required for light to travel along a path...Ch. 28 - Prob. 76ECh. 28 - What might we assume about the distribution of...Ch. 28 - Early astronomers such as Kepler and Newton...Ch. 28 - What force allows dark matter to clump?Ch. 28 - Why doesnt dark matter clump together as...Ch. 28 - If dark matter is affected by gravity, might there...Ch. 28 - What is the relationship between dark energy and...Ch. 28 - Is space just the absence of matter?Ch. 28 - What is one important difference between dark...Ch. 28 - Why is dark energy not called the dark force?Ch. 28 - The y-axis in the largest graph of Figure 28.27 is...Ch. 28 - Mass can transform into energy, and energy can...Ch. 28 - If the universe were unchanging and there were an...Ch. 28 - Prob. 89ECh. 28 - If we cant even predict the weather, how can we...Ch. 28 - Prob. 91DQCh. 28 - Prob. 92DQCh. 28 - Prob. 93DQCh. 28 - Prob. 94DQCh. 28 - Prob. 95DQCh. 28 - Choose the BEST answer to the question or the BEST...Ch. 28 - If the universe stopped expanding at this very...Ch. 28 - What percentage of galaxies were created during...Ch. 28 - What do cosmic inflation and dark energy have in...Ch. 28 - Light bends in a gravitational field. Why isnt...Ch. 28 - Time slows in a gravitational field. Would time...Ch. 28 - Prob. 7RATCh. 28 - Dark matter is (a) ordinary matter that is no...Ch. 28 - Space in our local universe is (a) not empty. (b)...Ch. 28 - Which theory for the fate of the universe assumes...
Additional Science Textbook Solutions
Find more solutions based on key concepts
Write each number in decimal form.
33. 1.4 × 100
Applied Physics (11th Edition)
Figure 15.23 shows a cork suspended from the bottom of a sealed container of water. The container is on a turnt...
Essential University Physics: Volume 1 (3rd Edition)
SETI researchers announced today that if they receive a message from a civilization located on the other side o...
Life in the Universe (4th Edition)
What are the two greenhouse gases most responsible for absorbing infrared light in Earth’s atmosphere?
Lecture- Tutorials for Introductory Astronomy
The pV-diagram of the Carnot cycle.
Sears And Zemansky's University Physics With Modern Physics
The correct option.
College Physics: A Strategic Approach (3rd Edition)
Knowledge Booster
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
- What is the evidence that star formation began when the universe was only a few hundred million years old?arrow_forwardStars form in the Milky Way at a rate of about 1 solar mass per year. At this rate, how long would it take for all the interstellar gas in the Milky Way to be turned into stars if there were no fresh gas coming in from outside? How does this compare to the estimated age of the universe, 14 billion years? What do you conclude from this?arrow_forwardSuppose the stars in an elliptical galaxy all formed within a few million years shortly after the universe began. Suppose these stars have a range of masses, just as the stars in our own galaxy do. How would the color of the elliptical change over the next several billion years? How would its luminosity change? Why?arrow_forward
- A galaxy at a distance of 25 Mpc has a recession velocity of 1875 km/sec. What is Hubble’s constant based on this one galaxy? Why is this not a good way to determine Hubble’s constant? Galaxy NGC 123 has a velocity away from us of 1,320 km/s and the Hubble Constant's value is 70 km/s/Mpc. How far away is the galaxy according to Hubble's Law?arrow_forwardPretend that galaxies are spaced evenly, 4.0 Mpc apart, and the average mass of a galaxy is 1.0 x 101 M What is the average density (in kg/m³) of matter in the universe? (Note: The volume of a sphere is 4 -ar, and the mass of the sun is 2.0 x 1030 kg.) kg/m3 Which model universe does this density value support? flat open closedarrow_forwardFigure 2 shows the "rotation curve" of NGC 2742. It plots the “radial velocity (V)" (how fast material is moving either toward or away from us) that is measured for objects at different distances (R = radius") from the center of the galaxy. The center of the galaxy is at 0 kpc (kiloparsecs) with a speed of 9 km/sec away from us. (These velocities have been corrected for the observed tilt of the galaxy and represent true orbital velocities of the stars and gas.) 200 100 U4779 -100 As you can see, one side of the galaxy is moving with a negative velocity (spinning toward us), while the other side has a positive velocity (spinning away from us). Using Newton's gravity equation, we will be able to determine the gravitational mass of the entire galaxy and how the mass varies versus distance from the galaxy's center. -200 -8 8 -4 Radius (kpc) Read the following text carefully and follow the instructions: Select five radii spaced evenly from 0-10 kpc across the galaxy. Your selections should…arrow_forward
- Assume that the number density of stars in the Milky Way is 0.14 pc-3. (e) There are 10" stars uniformly distributed across the galaxy. Also assume that there is one supernova every 30 years and all of them have same luminosity. Find the probablity, P, of a supernova causing extinction on Earth in total life span of the Sun.arrow_forwardConsider the Milky Way disk, which has a 50 kpc diameter and a total height of 600 pc. Suppose that the Sun orbits precisely at the mid-plane of the disk in a circular orbit. Supernovae explosions happen randomly throughout the disk at a rate of about 2 per 100 years. Consider a spherical region around the Sun with a radius of 300 pc. Ignore the Milky Way bulge and halo in this problem; assume the Milky Way disk is perfectly uniform and extends all the way through the region of the bulge. (I.e., the Milky Way is modeled *only* as a cylindrical disk--like a hockey puck-- with constant density throughout.) If a particular supernova goes off at a random location within the disk, what is the probability that it went off in the 300 pc radius spherical region near the Sun? Express your probability as a percentage (but without writing the percent sign). [Hint: there is a 100% probability that the supernova went off somewhere in the volume of the Milky Way disk; there is a 50% probability that…arrow_forwardIf you will compare the balloon to our universe, with the dots / markings as galaxies or galaxy clusters, what can you say about the distances of the galaxies as continuously expands?arrow_forward
- Explain the Higher-Order Systems?arrow_forwardIn the reading, you were told that there were roughly 10,000 galaxies in the image of the Hubble Ultra Deep Field alone. The image is roughly 10 square arcminutes and there are roughly 1.5*10^8 square arcminutes composing the entire sky. With that in mind and assuming that the Hubble Ultra Deep Field represents an average part of the sky, roughly how many galaxies may exist in the observable universe? (Please include commas for every factor of 1,000; for example 2,343,567,890)arrow_forwardGlobular clusters revolve around the Galaxy in highly elliptical orbits. Where would you expect the clusters to spend most of their time? (Think of Kepler’s laws.) At any given time, would you expect most globular clusters to be moving at high or low speeds with respect to the center of the Galaxy? Why? (If you would like to learn more about globular clusters, read Section 22.2 of the book, though it is not necessary to answer this question)arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Stars and Galaxies (MindTap Course List)PhysicsISBN:9781337399944Author:Michael A. SeedsPublisher:Cengage LearningAstronomyPhysicsISBN:9781938168284Author:Andrew Fraknoi; David Morrison; Sidney C. WolffPublisher:OpenStaxFoundations of Astronomy (MindTap Course List)PhysicsISBN:9781337399920Author:Michael A. Seeds, Dana BackmanPublisher:Cengage Learning
Stars and Galaxies (MindTap Course List)
Physics
ISBN:9781337399944
Author:Michael A. Seeds
Publisher:Cengage Learning
Astronomy
Physics
ISBN:9781938168284
Author:Andrew Fraknoi; David Morrison; Sidney C. Wolff
Publisher:OpenStax
Foundations of Astronomy (MindTap Course List)
Physics
ISBN:9781337399920
Author:Michael A. Seeds, Dana Backman
Publisher:Cengage Learning
General Relativity: The Curvature of Spacetime; Author: Professor Dave Explains;https://www.youtube.com/watch?v=R7V3koyL7Mc;License: Standard YouTube License, CC-BY