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Krane - Modern Physics 3/e (Homework)

James Finch

Physics - College, section 1, Fall 2019

Instructor: Dr. Friendly

Current Score : 9 / 22

Due : Monday, January 28, 2030 00:00 EST

Last Saved : n/a Saving...  ()

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Points
1 2 3 4 5 6
–/4 3/3 0/3 –/3 6/6 –/3
Total
9/22 (40.9%)

  • Instructions

    Here are some textbook questions from Modern Physics 3/e by Kenneth S. Krane published by John Wiley & Sons, Inc.

    Click here for a list of all of the questions coded in WebAssign. This demo assignment allows many submissions and allows you to try another version of the same question for practice wherever the problem has randomized values.

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1. –/4 points krane3 2.p.050.nva My Notes
Question Part
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Submissions Used
1 2 3 4
–/1 –/1 –/1 –/1
0/50 0/50 0/50 0/50
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–/4
 
Suppose an observer O measures a particle of mass m moving in the x direction to have speed v, energy E, and momentum p. Observer O', moving at speed u in the x direction, measures v', E ', and p' for the same object.
(a) Use the Lorentz velocity transformation to find E'  and p' in terms of m, u, v and c.
E ' =
p' =

(b) Reduce
E ' 2 − (p'c)2
 to its simplest form. (Use the following as necessary: m, u, v and c.)
E ' 2 − (p'c)2 =


Interpret the result.
    

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2. 3/3 points  |  Previous Answers krane3 11.p.001.nva My Notes
Question Part
Points
Submissions Used
1 2 3
1/1 1/1 1/1
1/50 1/50 2/50
Total
3/3
 
Consider the packing of hard spheres in the simple cubic geometry of the figure below.
Imagine eight spheres in contact with their nearest neighbors, with their centers at the corners of the basic cube.
(a) What fraction of the volume of each sphere is inside the volume of the basic cube?
Correct: Your answer is correct.

(b) Let r be the radius of each sphere and let a be the length of a side of the cube. Express a in terms of r.
a =
2r
Correct: Your answer is correct.

(c) What fraction of the volume of the cube is taken up by the portions of the spheres? This fraction is called the packing fraction.
Correct: Your answer is correct.

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3. 0/3 points  |  Previous Answers krane3 12.p.004.nva My Notes
Question Part
Points
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1 2 3
0/1 0/1 0/1
1/50 1/50 1/50
Total
0/3
 
Find the nuclear radius of 16O; 7Li; 197Au. (Use R0 = 1.2 10-15 m as necessary.)
(a)    16O
Incorrect: Your answer is incorrect. fm

(b)    7Li
Incorrect: Your answer is incorrect. fm

(c)    197Au
Incorrect: Your answer is incorrect. fm

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4. –/3 points krane3 12.p.033.nva My Notes
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1 2 3
–/1 –/1 –/1
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–/3
 
The figure below suggests that the Rutherford scattering formula fails for 60° scattering when K is about 28 MeV. Use the results derived in Chapter 6 to find the closest distance rmin between alpha particle and nucleus for this case, and compare with the nuclear radius R208-Pb of 208Pb. (The constant R0 is approximately equal to 1.2 10-15 m.)
rmin
 = fm
rmin
R208-Pb
 =
Deviations from the Rutherford formula in scattering from 208Pb are observed for alpha-particle energies above 27 MeV.

Suggest a possible reason for any discrepancy.

This answer has not been graded yet.

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5. 6/6 points  |  Previous Answers krane3 14.p.001.nva My Notes
Question Part
Points
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1 2 3 4 5 6
1/1 1/1 1/1 1/1 1/1 1/1
1/50 1/50 1/50 1/50 1/50 1/50
Total
6/6
 
Identify the interaction responsible for the following decays (approximate half-lives are given in parentheses).
(a)    
Δ* → p + π (10−23 s)
     Correct: Your answer is correct.

(b)    
η → γ + γ (10−18 s)
     Correct: Your answer is correct.

(c)    
K+ → μ+ + νμ (10−8 s)
     Correct: Your answer is correct.

(d)    
Λ0 → p + π− (10−10 s)
     Correct: Your answer is correct.

(e)    
η' → η + 2π (10−21 s)
     Correct: Your answer is correct.

(f)    
K0 → π+ + π− (10−10 s)
     Correct: Your answer is correct.

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6. –/3 points krane3 14.p.010.nva My Notes
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–/1 –/1 –/1
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–/3
 
Carry out the calculations of mc2 for the three decays of the figure below.
figure (a)     mc2 = MeV
figure (b)     mc2 = MeV
figure (c)     mc2 = MeV

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