Time Dilation: A 30-year-old astronaut goes off on a long-term mission in a spacecraft that travels at speeds close to that of light. The mission lasts exactly 20 years as measured on Earth. Biologically speaking, at the end of the mission, the astronaut's age would be
A. more than 50 years.
B. exactly 50 years.
C. less than 50 years.
D. exactly 30 years.
E. exactly 25 years.
Answer: C
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Suppose an unpowered but moving railroad car receives some coal (basically at rest) from a stationary conveyor belt. This coal therefore only carries chemical energy into the car. This mass transfer will
A. Cause the car’s speed to increase. B. Cause the car’s speed to decrease. C. Have no effect on the car’s speed.
The work done by static friction can be:
a. positive. b. negative. c. zero. d. Any of the above.
An ideal gas starts in state A at temperature T. The gas expands to new volume V by an adiabatic process and its final temperature is T?. What is the relationship between T and T??
A) T = T? B) T > T? C) T < T? D) The answer depends on the heat capacity of the ideal gas. E) The answer depends on the number of moles of gas and the pressure.
A material has an index of refraction of 1.92 for light from a 560 nm source. What is the speed of light for this wavelength within the material? (c = 3.00 × 10^8 m/s)
a. 2.19 × 10^8 m/s c. 1.56 × 10^8 m/s b. 4.68 × 10^8 m/s d. 1.92 × 10^8 m/s