2 Cosmic Ray A cosmic-ray particle has been observed (indirectly) with an estimated energy of 16 J, or about 102⁰ eV.* Suppose this particle was a proton (me² ≈ 10⁹ eV). (a) What was the velocity of the proton relative to the earth? Warning! Most calculators do not carry around enough digits to give an answer other than u = c, but this is not the speed of the particle. Express your result in terms of the fractional difference between the velocity of the particle and the velocity of light: c=2=D=1-8 (b) The Milky Way is about 105 light years across. If a photon and this proton raced across the galaxy, by what distance would the photon win the race, as measured by an observer at rest with respect to the galaxy? (c) How long would it take the proton to cross our galaxy, as measured by a clock carried along with the proton?

2 Cosmic Ray A cosmic-ray particle has been observed (indirectly) with an estimated energy of 16 J, or about 102⁰ eV.* Suppose this particle was a proton (me² ≈ 10⁹ eV). (a) What was the velocity of the proton relative to the earth? Warning! Most calculators do not carry around enough digits to give an answer other than u = c, but this is not the speed of the particle. Express your result in terms of the fractional difference between the velocity of the particle and the velocity of light: c=2=D=1-8 (b) The Milky Way is about 105 light years across. If a photon and this proton raced across the galaxy, by what distance would the photon win the race, as measured by an observer at rest with respect to the galaxy? (c) How long would it take the proton to cross our galaxy, as measured by a clock carried along with the proton?

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter28: Special Relativity

Section: Chapter Questions

Problem 34PE: (a) All but the closest galaxies are receding from our own Milky Way Galaxy. If a galaxy 12.0109ly...

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Protons in an accelerator at the Fermi National Laboratory near Chicago are accelerated to an energy of 400 times their rest energy. (a) What is the speed of these protons? (b) What is their kinetic energy in MeV?
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