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) 20 y B) 12 y C) 10 y D) 15 y E) 18 y
E
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That the radio lobes radiate synchrotron radiation indicates that
a. high speed electrons are spiraling through a magnetic field. b. the source of the radio jets must be a black hole. c. the source of the radio energy is rotating rapidly. d. the central galaxy must be a giant elliptical galaxy. e. the central galaxy must rotate about two nearly perpendicular axes.
Which of the following claims can be tested by scientific means?
a. the final thought of Abraham Lincoln were about the fate of his country b. God exists c. blue is the best color for walls d. people born when the sun is in constellation of Leo are more financially successful than other people
__________is an isotope of hydrogen in which the nucleus contains a proton and a neutron
A) Deuterium B) Neutrino C) Tritium D) Hydrogen-4
Components: The x component of vector 
is 8.7 units, and its y component is -6.5 units. The magnitude of 
is closest to
A. 9.9 units. B. 7.9 units. C. 8.9 units. D. 11 units. E. 12 units.