A spaceship visits Alpha Centauri and returns to Earth. Alpha Centauri is 4.5 light-years from Earth (our second closest star). The spaceship travels at one-half the speed of light for essentially all of its expedition
(a) How long was the ship gone according to an observer on the Earth? (b) How long was the ship gone according to an observer on the spaceship?
(a) 10. light-years
(b) 7.8 years
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If helium nuclei and protons are each accelerated from rest through the same potential difference, how do the resulting speeds compare?
A. the protons attain twice the speed of the helium nuclei B. the protons attain 1.4 times the speed of the helium nuclei C. the helium nuclei attain twice the speed of the protons D. the helium nuclei attain 1.4 times the speed of the protons E. they both attain the same speed
When water of mass m and specific heat c is heated from absolute temperature T1 to absolute temperature T2, its change in entropy is
a. cm ln(T2/T1) b. cm (T2/T1) c. cm (T2 - T1)/T1 d. cm (T2 - T1)/T2 e. cm (T2 - T1)/(T2 + T1)
If the Sun were replaced by a one solar mass black hole:
A) all terrestrial planets would fall in immediately. B) we would still orbit it in a period of one year. C) we would immediately escape into deep space, driven out by its radiation. D) our clocks would all stop. E) life here would be unchanged.
On a force vs. position graph, the area under curve is a representation of
A) force. B) position. C) kinetic energy. D) potential energy. E) work.