# Theory of Rlelativity

Topics: Photon, Electron, Special relativity Pages: 2 (370 words) Published: May 19, 2008
1) Annual energy consumption in the United States (Q24; Giancoli Chap 26) The total annual energy consumption in the United States is about 8 10 J. 19 How much mass would have to be converted to energy to fuel this need?

2) The nearest star to Earth (Q49; Giancoli Chap 26)
The nearest star to Earth is Proxima Centauri, 4.3 light-years away. (a) At what constant velocity must a spacecraft travel from Earth if it is to reach the star in 4.0 years, as measured by travellers on the spacecraft? (b) How long does the trip take according to Earth observers?

3) Electron in a uniform magnetic field (Q54; Giancoli Chap 26) An electron ( . kg) 31 9 11 10m enters a uniform magnetic field B 1.8 T, and moves perpendicular to the
field lines with a speed v 0.92c. What is the radius of curvature of its path? See hint for Problem 42. 4) Producing an electron and a positron (Q53; Giancoli Chap 26) What minimum amount of electromagnetic energy is needed to produce an electron and a positron together? A positron is a particle with the same rest mass as an electron, but has the opposite charge. (Note that electric charge is conserved in this process. See Section 27–6.)

5) Running a 100-W light bulb on matter (Q52; Giancoli Chap 26) How many grams of matter would have to be totally destroyed to run a 100-W light bulb for 1 year? 6) Studying physics (Q65; Giancoli Chap 26)

A farm boy studying physics believes that he can fit a 15.0-m-long pole into a 12.0-m-long barn if he runs fast enough (carrying the pole). Can he do it? Explain in detail. How does this fit with the idea that when he is running the barn looks even shorter to him than 12.0 m?

7) Producing electromagnetic energy (Q55; Giancoli Chap 26)
A negative muon traveling at 33% the speed of light collides head on with a positive muon traveling at 50% the speed of light. The two muons (each of rest mass
2 105.7 MeV c
) annihilate, and produce how much
electromagnetic energy?

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