When a spinning ice skater pulls in his arms, he spins faster because
A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation.
B) there is less friction with the air.
C) there is less friction with the ice.
D) there exists an unbalanced reaction force.
A
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Thermodynamic Devices: A Carnot air conditioner has a coefficient of performance of 17.0 and removes 72.0 MJ of heat from the interior of a house every hour. How much power does it consume?
A. 1180 W B. 1320 W C. 520 kW D. 3.14 MW E. 1.25 MW
A positively charged electron is
A) called a positron. B) called a muon. C) called a proton. D) not found in nature. E) called a pion.
How many megabytes are there in a gigabyte?
a. 10 b. 1000 c. 1000000 d. none of the above
A space exploration satellite is orbiting a spherical asteroid whose mass is 4.65 × 1016 kg and whose radius is 39,600 m, at an altitude of 12,400 m above the surface of the asteroid
In order to make a soft landing, Mission Control sends it a signal to fire a short burst of its retro rockets to change its speed to one that will put the satellite in an elliptical orbit with a periapsis (the distance of closest approach, as measured from the center of the asteroid) equal to the radius of the asteroid. What is the speed of the satellite when it reaches the surface of the asteroid? G = 6.67 x 10-11 N•m2/kg2. A) 4.32 m/s B) 6.11 m/s C) 7.18 m/s D) 9.43 m/s E) 5.74 m/s