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Bennett et al - The Cosmic Perspective (Homework)

James Finch

Astronomy, section 1, Fall 2010

Instructor: Dr. Friendly

Current Score: 2/15

Due: Tuesday, September 14, 2010 08:30 EDT

About this Assignment

Question
Points
1 2 3 4 5
1/2 0/5 0/3 0/3 1/2
Total
2/15

Description

Here are some textbook questions from The Cosmic Perspective 2/e by Bennett, Donahue, Schneider, and Voit published by Addison Wesley. Click here for a list of all of the questions coded in WebAssign.


Instructions

This demo assignment allows many submissions and makes the answer key available after the first submission so you can see the correct answers. (Typically, the answer key is posted after the due date!)



1. 1/2 points All Submissions Notes Question: BDSVastro2 1.P.09.
Question part
Points
Submissions
1 2
1 0/1
2/50 0/50
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1/2
 
Suppose the Earth's axis has no tilt. Would we still have seasons?
    

Your answer is correct.


Why or why not?


2. –/5 points Notes Question: BDSVastro2 1.P.14.
Question part
Points
Submissions
1 2 3 4 5
0/1 0/1 0/1 0/1 0/1
0/50 0/50 0/50 0/50 0/50
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0/5
 
Imagine that you could drive your car in space at a constant speed of 170 km/hr. (In reality, the law of gravity would make driving through space at a constant speed all but impossible.)
(a) How long would it take to circle the Earth in low orbit? (Hint: Use the Earth's circumference of 40,087 km.)
Enter a number.
 days
(b) Suppose you started driving from the Sun. How long would it take to reach Earth? Use the data in Table 1.1.


Table 1.1

Enter a number.
 years
How long would it take to reach Neptune?
Enter a number.
 years
(c) How long would it take to drive the 4.4 light years to Alpha Centauri? (Hint: You'll need to convert the distance to kilometers.)
Enter a number.
 years
(d) The Voyager 2 spacecraft is traveling about 50,000 km/hr. At this speed, how long would it take to reach Alpha Centauri (if it were headed in the right direction, which it is not)?
Enter a number.
 years


3. –/3 points Notes Question: BDSVastro2 4.P.13.
Question part
Points
Submissions
1 2 3
0/1 0/1 0/1
0/50 0/50 0/50
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0/3
 
Suppose that, through a horrific act of an angry god (or a very powerful alien, if you prefer), all the mass in your body was suddenly converted into energy according to the formula E = mc2. How much energy would be produced? Assume that your mass is 65 kg. (Hint: Multiply your mass in kilograms by c2.)
Enter a number.
 J
Compare this to the energy released by a 1 megaton hydrogen bomb (see Table 4.1).
Enter a number.
 times


4. –/3 points Notes Question: BDSVastro2 14.P.13.
Question part
Points
Submissions
1 2 3
0/1 0/1 0/1
0/50 0/50 0/50
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0/3
 
The Sun's average surface temperature is about 5,800 K. Use Wien's law to calculate the wavelength of peak thermal emission from the Sun.
Enter a number.
 nm
What color does this wavelength correspond to in the visible light spectrum?
    


In light of your answer, why do you think the Sun appears white or yellow to our eyes?


5. 1/2 points All Submissions Notes Question: BDSVastro2 19.P.07.
Question part
Points
Submissions
1 2
1 0/1
2/50 0/50
Total
1/2
 
Decide whether the following statement is sensible.
We can't see galaxies beyond the cosmological horizon because they are moving away from us faster than the speed of light.
    

Your answer is correct.


Explain why it is or is not.

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