Understanding Our Universe
3rd Edition
ISBN: 9780393614428
Author: PALEN, Stacy, Kay, Laura, Blumenthal, George (george Ray)
Publisher: W.w. Norton & Company,
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Chapter 16, Problem 21QAP
(a)
To determine
The significance of the discovery made by astronomers.
(b)
To determine
The reason why Hubble discovery was important among all the discoveries of the 20th century.
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An astronomer observed the motions of some galaxies. Based on his observations, he made the following statements. Which one of them is most likely to be false? Take Hubble's constant to be 67 km/s/Mpc.
A. A galaxy observed to be moving away from us at a speed of 70 km/s is at a distance of about 1 Mpc from us.
B. A galaxy observed to be moving away from us at a speed of 700 km/s is at a distance of about 10 Mpc from us.
C. A galaxy observed to be moving away from us at a speed of 7000 km/s is at a distance of about 100 Mpc from us.
D. A galaxy observed to be moving away from us at a speed of 70000 km/s is at a distance of about 1 Gpc from us.
Is the answer D? Thank you!
The mass density of our universe is measured to be about 10-29 kg/m3. If an arbitrary point is chosen as the center, how large is the radius of a spherical surface centered at the point so that the mass enclosed in the surface will become a blackhole observed by someone outside the surface?
A. 4.2 trillion light years
B. 420 billion light years
C. 42 billion light years
D. 4.2 billion light years
Is the answer D? Thanks!
Observations of distant galaxies show
they appear older than they really are.
the size of the visible universe is getting smaller.
O galaxies move but they remain at constant distances from one another.
O they are moving away from us.
O they are all located inside the Milky Way Galaxy.
Chapter 16 Solutions
Understanding Our Universe
Ch. 16.1 - Prob. 16.1CYUCh. 16.2 - Prob. 16.2CYUCh. 16.3 - Prob. 16.3CYUCh. 16.4 - Prob. 16.4CYUCh. 16.5 - Prob. 16.5CYUCh. 16.6 - Prob. 16.6CYUCh. 16 - Prob. 1QAPCh. 16 - Prob. 2QAPCh. 16 - Prob. 3QAPCh. 16 - Prob. 4QAP
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- The Big Bang Theory is currently the most widely-accepted explanation for the origin of the Universe. As technology has emerged, new data has been collected to allow for a clearer understanding of how the Universe is changing and the possible things that might happen to it in the future. Which of the following is not a question that can be answered using scientific processes? o What was the cause of the Big Bang? o What is the type of energy emitted by celestial objects? o What is the rate at which the universe appears to be expanding? o What are the chemical elements that exist in the other parts of the galaxy?arrow_forwardYou are a passenger on a spaceship. As the speed of the spaceship increases, you would observe A. the length of your spaceship getting shorter. B. the length of your spaceship getting longer. C. the length of your spaceship varying erratically. D. nothing unusual about the length of your spaceship.arrow_forwardA galaxy is observed to recede from Earth with an approximate speed of 0.81c. Approximately how far d from Earth is this galaxy? Give an answer in units of megaparsecs (Mpc). d = ? Mpc How long ago t was the light that we see emitted by the galaxy? Give an answer in units of years. t = ? yearsarrow_forward
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