A set of twins, Andrea and Courtney, are initially 10 years old
While Courtney remains on Earth, Andrea rides on a spaceship which travels away from Earth at a speed of 0.60c for five years (as measured by Courtney), then immediately turns around and comes back at 0.60c. When Andrea returns, Courtney is 20 years old. How old is Andrea upon her return?
A) 10 y
B) 12 y
C) 15 y
D) 18 y
E) 20 y
Answer: D
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During a thermodynamic process, the entropy of a certain system decreases by 1.0 J/K. What are some possible entropy changes that could have occurred within the system's surrounding environment?
1.Its entropy could have also decreased by 1.0 J/K. 2.Its entropy could have remained constant. 3.Its entropy could have increased by 2.5 J/K. 4.All of these could have occurred.
A moving object's mass is twice its rest mass. Its length (in the direction of travel) must therefore be
A) one-half its proper length. B) twice its proper length. C) one-fourth its proper length. D) four times its proper length. E) times its proper length.
A setting Sun appears red due to
A) scattering of lower frequencies by larger particles in the air. B) light's longer path through air at sunset. C) lower frequencies of light emitted during sunset. D) absorption by smaller particles in the air.
Coulomb's Law: Two identical small charged spheres are a certain distance apart, and each one initially experiences an electrostatic force of magnitude F due to the other. With time, charge gradually diminishes on both spheres by leaking off. When each of the spheres has lost half its initial charge, what will be the magnitude of the electrostatic force on each one?
A. 1/16 F
B. 1/8 F
C. 1/4 F
D. 1/2 F
E. 1/
F