bei48482_FM

516 Appendix

Answers to Odd-Numbered Exercises

CHAPTER 1

1. More conspicuous.


2. No, because the observer in the spacecraft will find a longer time interval than
   an observer on the ground, not a shorter time interval.


3. (a) 3.93 s. (b) To B, A’s watch runs slow.


4. 2.6 108 m/s.


5. 210 m.


6. 578 nm.


7. 1.34 104 m/s.


8. 6 ft; 2.6 ft.


9. 3.32 10 ^8 s.


10. 14°.


11. 5.0 y.


12. If pmv,an event that conserves momentum in one inertial frame would not
    conserve momentum to observers in other inertial frames in relative motion, so
    momentum would not then be a useful quantity in physics.


13. 6.0 10 ^11.


14. ( 3 2)c.


15. 1.88 108 m/s; 1.64 108 m/s.


16. 0.9989c.


17. 0.294 MeV.


18.  1019 eV; 105 y.


19. 0.383 MeV/c.


20. 885 keV/c.


21. 0.963c; 3.372 GeV/c.


22. 874 MeV/c^2 ; 0.37c.


23. 1.97 ms.


24. (a) tan^1.

(b) As →c, tan→0 and →0. This means that the stars appear farther

forward in the field of view of the porthole than they do when 0.

55. (a) 0.800c; 0.988c.(b) 0.900c; 0.988c.

CHAPTER 2

1. Less conspicuous.


2. KEmaxis proportional to minus the threshold frequency 0.


3. 1.77 eV.


4. 1.72 1030 photons/s.


5. (a) 4.2 1021 photons/m^2 .(b) 4.0 1026 W; 1.2 1045 photons/s.
   (c) 1.4 1013 photons/m^3.


6. 180 nm.


7. 539 nm; 3.9 eV.


8. 0.48 A.


9. 6.64 10 ^34 J s; 3.0 eV.


10. In the reference frame of the electron at rest, the photon momentum must equal
    the final electron momentum p. The corresponding photon energy is pcbut the

sin 1 ^2 c^2

cos c

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