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Chapter 28 | Special Relativity
71. Construct Your Own Problem
Consider a highly relativistic particle. Discuss what is meant by the term “highly relativistic.” (Note that, in part, it means that the particle cannot be massless.) Construct a problem in which you calculate the wavelength of such a particle and show that it is very nearly the same as the wavelength of a massless particle, such as a photon, with the same energy. Among the things to be considered are the rest energy of the particle (it should be a known particle) and its total energy, which should be large compared to its rest energy.
72. Construct Your Own Problem
Consider an astronaut traveling to another star at a relativistic velocity. Construct a problem in which you calculate the time for the trip as observed on the Earth and as observed by the astronaut. Also calculate the amount of mass that must be converted to energy to get the astronaut and ship to the velocity travelled. Among the things to be considered are the distance to the star, the velocity, and the mass of the astronaut and ship. Unless your instructor directs you otherwise, do not include any energy given to other masses, such as rocket propellants.
Test Prep for AP® Courses a. 28.1 Einstein’s Postulates b.
1. Which of the following statements describes the Michelson-
Morley experiment? c.
a. The speed of light is independent of the motion of the
source relative to the observer. d.
b. The speed of light is different in different frames of reference.
c. The speed of light changes with changes in the observer.
d. The speed of light is dependent on the motion of the source.
28.4 Relativistic Addition of Velocities
2. What happens when velocities comparable to the speed of light are involved in an observation?
a. Newton’s second law of motion, , governs the motion of the object.
b. Newton’s second law of motion, , no longer
governs the dynamics of the object.
c. Such velocities cannot be determined mathematically.
d. None of the above
3. How is the relativistic Doppler effect different from the classical Doppler effect?
28.6 Relativistic Energy
4. A mass of 50 g is completely converted into energy. What is the energy that will be obtained when such a conversion takes place?
5. Show that relativistic kinetic energy becomes the same as classical kinetic energy when .
6. The relativistic energy of a particle in terms of momentum is given by:

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