A proton with mass 1.67 10-27 kg moves with a speed of 0.800c in an accelerator. What is its relativistic momentum? (c = 3.00 108 m/s)
a. 2.40 10-19 kgm/s
c. 0.530 10-19 kgm/s
b. 6.68 10-19 kgm/s
d. 3.76 10-19 kgm/s
[Ques. 2] Doubling the momentum of a particle:
a. does not change its relativistic total energy.
b. quadruples its relativistic total energy.
c. doubles its relativistic total energy.
d. requires less of a speed increase as the speed increases.
[Ques. 3] As measured from the Earth, a spacecraft is moving at speed 0.80c when it releases a probe at speed 0.60c relative to the spacecraft in a forward direction. What would be the speed of the probe as measured from the Earth?
a. 0.70c
c. c
b. 0.81c
d. 0.95c
[Ques. 4] As measured from the Earth, a spacecraft is moving at speed 0.80c toward a second spacecraft moving at speed 0.60c back toward the first spacecraft. What is the speed of the first spacecraft as viewed from the second spacecraft?
a. 0.81c
c. 0.38c
b. 0.95c
d. 0.20c
[Ques. 5] As measured from the Earth, a spacecraft is moving at speed 0.80c toward another spacecraft moving at speed 0.60c in the same direction, i.e., the first spacecraft is catching up with the second spacecraft. What is the speed of the first spacecraft as viewed from the second spacecraft?
a. 0.38c
c. 0.38c
b. 0.20c
d. not given
[Ques. 6] A particle is moving the +x direction at speed c/2 . Another particle is moving in the x direction at speed c/2 toward the first particle. Which of the following best describes the speed of one particle as seen by an observer moving with the other particle?
a. c
c. some value more than 3c/4
b. some value less than 3c/4
d. 3c/4
[Ques. 7] Our best measurements from Earth indicate that the star system Alpha Centauri is 4.2 light-years away. Suppose some of our astronauts traveled there at a speed v = 0.90c. What would the astronauts measure as the distance to Alpha Centauri?
a. 1.3 lightyears
c. 1.8 lightyears
b. 4.0 lightyears
d. 2.7 lightyears
[Ques. 8] A muon formed high in Earth's atmosphere travels at a speed 0.9900c for a distance (as we see it) of 9200 m before it decays. How far does the muon travel as measured in its frame?
a. 2596 m
c. 4554 m
b. 1298 m
d. 649 m
[Ques. 9] A knight on horseback holds a 10-m lance. The horse can run at 0.78c. (It wins most of its races) How long will the lance appear to a person that is standing still on the ground as the horse runs past?
a. 7.1 m
c. 10 m
b. 15 m
d. 6.3 m
[Ques. 10] The short lifetime of muons created in the upper atmosphere of the Earth would not allow them to reach the surface of the Earth unless their lifetime increased by time dilation. From the reference system of the muons, the muons can reach the surface of the Earth because:
a. time dilation increases their energy.
b. time dilation increases their velocity.
c. the relativistic speed of the Earth toward them is added to their velocity.
d. length contraction decreases the distance to the Earth.
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