The Cosmic Perspective (8th Edition)
8th Edition
ISBN: 9780134127552
Author: Bennett
Publisher: PEARSON
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Textbook Question
Chapter 12, Problem 49EAP
Be sure to show all calculations clearly and state your final answers in complete sentences.
- Adding Up Asteroids. It’s estimated that there are a million asteroids 1 kilometer across or larger. If a million asteroids 1 kilometer across were all combined into one object, how big would it be? How many 1-kilometer asteroids would it take to make an object as large as Earth? (Hint: You can assume they’re spherical. The expression for the volume of a sphere is jirr3, where r is the radius.)
- Impact Energies. A relatively small impact crater 20 kilometers in diameter could be made by a comet 2 kilometers in diameter traveling at 30 kilometers per second (30,000 m/s).
- Assume that the comet has a total mass of 4.2 x 10'? kilograms. What is its total kinetic energy? (Hint: The kinetic energy is equal to Jmiz2, where m is ihe comet’s mass and v is its speed. If you use mass in kilograms and velocity in m/s, the answer for kinetic energy will have units of joules.)
- Convert your answer from part a to an equivalent in megatons of TNT, the unit used for nuclear bombs. Comment on the degree of devastation the impact of such a comet could cause if it struck a populated region on Earth. (Hint: One megaton of TNT releases 4.2 X 10ls joules of energy.)
- The "Near Miss" of Toaiatis. The 5-kilometcr asteroid Toutatis paBsed a mere 1.5 million kilometers from Earth in 2004. Suppose Toutatis were destined to pass somewhere within 1.5 million kilometers of Earth. Calculate the probability that this "somewhere" would have meant that it slammed into Earth. Based on your result, do you think it is fair to call the 2004 passage a “near miss"? Explain. (Hint: You can calculate the probability by considering an imaginary dartboard of radius 1.5 million kilometers in which the bull's-eye has Earth’s radius, 6378 kilometers.)
- Room to Roam. It's estimated that there are a trillion comets in the Oort cloud, which extends out to about 50,000 AU. What is the total volume of the Oort cloud, in cubic AU? How much space does each comet have in cubic AU, on average? Take the cube root of the average volume per comet to find the comets’ typical spacing in AU. (Hints: For the purpose of this calculation, you can assume the Oort cloud fills the whole sphere out to 50,000 AU. The volume of a sphere is given by ywr3, where ris the radius.)
- Comet Temperatures. Find the “no greenhouse" temperatures for a comet at distances from the Sun of 50,000 AU (in the Oort cloud), 3 AU, and 1 AU (see Mathematical Insight 10.1). Assume that the comet reflects 3% of the incoming sunlight. At which location will the temperature be high enough for water ice to vaporize (about 150 K)? How do your results explain comet anatomy? Explain.
- Comet Dust Accumulation. A few hundred tons of comet dust arc added to Earth daily from the millions of meteors that enter our atmosphere. Estimate the time it would take for Earth to get 0.1 % heavier at this rate. Is this mass accumulation significant for Earth as a planet? Explain.
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In the previous lab, we calculated the area in between Mars' and Jupiter's orbit to be ~1.6e18 km2. Since there are roughly 750,000 asteroids, how much area (in km2) is available for one asteroid? Use this calculation to argue whether you are likely (or not) to hit an asteroid while flying through the asteroid belt.
(Hint: To answer the first part of the question, find the area per asteroid)
the area in between Mars' and Jupiter's orbit to be ~1.6e18 km2. Since there are roughly 750,000 asteroids, how much area (in km2) is available for one asteroid? Use this calculation to argue whether you are likely (or not) to hit an asteroid while flying through the asteroid belt.
(Hint: To answer the first part of the question, find the area per asteroid)
The Tunguska asteroid is estimated to have had a diameter of 50 m, and to have produced an explosion equivalent to 10 megatons of TNT (1 megaton = 4.2 x 1015 joules). Assume that the asteroid was a sphere with density 2 g/cm3. Using the kinetic energy formula K = ½ mv2, where m is the mass and v is the speed, to estimate the speed of the asteroid. Assume that all kinetic energy is converted into the energy of the explosion.
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Chapter 12 Solutions
The Cosmic Perspective (8th Edition)
Ch. 12 - Prob. 1VSCCh. 12 - Use the following questions to check your...Ch. 12 - Use the following questions to check your...Ch. 12 - Prob. 4VSCCh. 12 - Use the following questions to check your...Ch. 12 - 1. Briefly define asteroid. comet, dwarf planet,...Ch. 12 - Briefly describe asteroid sizes, shapes, masses,...Ch. 12 - 3. Distinguish between primitive meteorites and...Ch. 12 - 4. What do meteorites and spacecraft observations...Ch. 12 - Prob. 5EAP
Ch. 12 - Prob. 6EAPCh. 12 - Prob. 7EAPCh. 12 - How do we know the Kuiper belt and Oort cloud...Ch. 12 - Prob. 9EAPCh. 12 - Prob. 10EAPCh. 12 - Prob. 11EAPCh. 12 - Briefly describe the evidence suggesting that an...Ch. 12 - Prob. 13EAPCh. 12 - Prob. 14EAPCh. 12 - Prob. 15EAPCh. 12 - Prob. 16EAPCh. 12 - Prob. 17EAPCh. 12 - Prob. 18EAPCh. 12 - Prob. 19EAPCh. 12 - Prob. 20EAPCh. 12 - Prob. 21EAPCh. 12 - Prob. 22EAPCh. 12 - Prob. 23EAPCh. 12 - Prob. 24EAPCh. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Choose the best answer to each of the following....Ch. 12 - Prob. 35EAPCh. 12 - Prob. 36EAPCh. 12 - Prob. 37EAPCh. 12 - Prob. 38EAPCh. 12 - Prob. 39EAPCh. 12 - Prob. 40EAPCh. 12 - Prob. 41EAPCh. 12 - Comet Tails. Describe in your own words why comets...Ch. 12 - Prob. 43EAPCh. 12 - Prob. 44EAPCh. 12 - Prob. 45EAPCh. 12 - Prob. 46EAPCh. 12 - Prob. 47EAPCh. 12 - Be sure to show all calculations clearly and state...Ch. 12 - Be sure to show all calculations clearly and state...Ch. 12 - Prob. 50EAPCh. 12 - Rise of the Mammals. Suppose the impact 65 million...Ch. 12 - Prob. 52EAPCh. 12 - Prob. 53EAPCh. 12 - Prob. 54EAPCh. 12 - Prob. 55EAP
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