A set of twins, Andrea and Courtney, are initially 10 years old. While Courtney remains on Earth,
Andrea rides on a space ship which travels away from Earth at a speed of 0.6c for five years (as measured by Courtney), then turns around and comes back at 0.6c. When Andrea returns, Courtney is 20 years old. How old is Andrea upon her return?
A) 10 years
B) 12 years
C) 15 years
D) 18 years
E) 20 years
D
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Weight and g: An object weighs 432 N on the surface of the earth. The earth has radius R. If the object is raised to a height of 3R above the earth's surface, what is its weight?
A. 108 N B. 48.0 N C. 27.0 N D. 305 N E. 144 N
Thermodynamic Devices: A refrigerator has a coefficient of performance equal to 4.2. How much work must be done on the operating gas in the refrigerator in order to remove 250 J of heat from the interior compartment?
A. 60 J B. 120 J C. 250 J D. 480 J E. 1050 J
______________ tides occur during the first-quarter and last-quarter moon phases
Fill in the blank(s) with correct word
A non-uniform, 80-g, meter stick balances when the support is placed at the 51.0-cm mark. At what location on the stick should a 5.0-g tack be placed so that the stick will balance at the 50.0 cm mark?
A) 16.0 cm B) 67.0 cm C) 66.0 cm D) 35.0 cm E) 34.0 cm