Physics for Scientists and Engineers with Modern Physics
10th Edition
ISBN: 9781337553292
Author: Raymond A. Serway, John W. Jewett
Publisher: Cengage Learning
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Chapter 13, Problem 37AP
Studies of the relationship of the Sun to our galaxy—the Milky Way—have revealed that the Sun is located near the outer edge of the galactic disc, about 30 000 ly (1 ly = 9.46 × 1015 m) from the center. The Sun has an orbital speed of approximately 250 km/s around the galactic center. (a) What is the period of the Sun’s galactic motion? (b) What is the order of magnitude of the mass of the Milky Way galaxy? (c) Suppose the galaxy is made mostly of stars of which the Sun is typical. What is the order of magnitude of the number of stars in the Milky Way?
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Studies of the relationship of the Sun to our galaxy— the Milky Way—have revealed that the Sun is located near the outer edge of the galactic disc, about 30 000 ly (1 ly 5 9.46 × 1015 m) from the center. The Sun has anorbital speed of approximately 250 km/s around the galactic center. (a) What is the period of the Sun’s galactic motion? (b) What is the order of magnitude of the mass of the Milky Way galaxy? (c) Suppose the galaxy is made mostly of stars of which the Sun is typical. What is the order of magnitude of the number of stars in the Milky Way?
A star near the visible edge of a galaxy travels in a uniform circular orbit. It is 43,500 ly (light-years) from the galactic center and has a speed of 275 km/s.
a.)Estimate the total mass of the galaxy based on the motion of the star. Gravitational constant is 6.674×10−11m3/(kg·s2) and mass of the Sun Ms=1.99 × 1030 kg.
b.)The total visible mass (i.e., matter we can detect via electromagnetic radiation) of the galaxy is 1011 solar masses. What fraction of the total mass of the galaxy is visible, according to this estimate?
Astronomical observations of our Milky Way galaxy indicate that it has a mass of about 8 ✕ 1011 solar masses. A star orbiting near the galaxy's periphery is 5.8 ✕ 104 light years from its center.
(a)
What should the orbital period (in y) of that star be?
y
(b)
If its period is 7.0 ✕ 107 y instead, what is the mass (in solar masses) of the galaxy? Such calculations are used to imply the existence of "dark matter" in the universe and have indicated, for example, the existence of very massive black holes at the centers of some galaxies.
solar masses
Chapter 13 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 13.1 - A planet has two moons of equal mass. Moon 1 is in...Ch. 13.2 - Prob. 13.2QQCh. 13.4 - Prob. 13.3QQCh. 13.6 - Prob. 13.4QQCh. 13 - Prob. 1PCh. 13 - During a solar eclipse, the Moon, the Earth, and...Ch. 13 - Determine the order of magnitude of the...Ch. 13 - Prob. 4PCh. 13 - Review. Miranda, a satellite of Uranus, is shown...Ch. 13 - (a) Compute the vector gravitational field at a...
Ch. 13 - A spacecraft in the shape of a long cylinder has a...Ch. 13 - An artificial satellite circles the Earth in a...Ch. 13 - Prob. 9PCh. 13 - A particle of mass m moves along a straight line...Ch. 13 - Use Keplers third law to determine how many days...Ch. 13 - Prob. 12PCh. 13 - Suppose the Suns gravity were switched off. The...Ch. 13 - (a) Given that the period of the Moons orbit about...Ch. 13 - How much energy is required to move a 1 000-kg...Ch. 13 - An object is released from rest at an altitude h...Ch. 13 - A system consists of three particles, each of mass...Ch. 13 - Prob. 18PCh. 13 - A 500-kg satellite is in a circular orbit at an...Ch. 13 - Prob. 20PCh. 13 - Prob. 21PCh. 13 - Prob. 22PCh. 13 - Ganymede is the largest of Jupiters moons....Ch. 13 - Prob. 24APCh. 13 - Voyager 1 and Voyager 2 surveyed the surface of...Ch. 13 - Prob. 26APCh. 13 - Prob. 27APCh. 13 - Why is the following situation impossible? A...Ch. 13 - Let gM represent the difference in the...Ch. 13 - A sleeping area for a long space voyage consists...Ch. 13 - Prob. 31APCh. 13 - Prob. 32APCh. 13 - Prob. 33APCh. 13 - Two spheres having masses M and 2M and radii R and...Ch. 13 - (a) Show that the rate of change of the free-fall...Ch. 13 - A certain quaternary star system consists of three...Ch. 13 - Studies of the relationship of the Sun to our...Ch. 13 - Review. Two identical hard spheres, each of mass m...Ch. 13 - Prob. 39APCh. 13 - Prob. 40APCh. 13 - Prob. 41APCh. 13 - Prob. 42APCh. 13 - As thermonuclear fusion proceeds in its core, the...Ch. 13 - Two stars of masses M and m, separated by a...Ch. 13 - The Solar and Heliospheric Observatory (SOHO)...
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