12) A satellite remains at the same position above the earth's surface at all times. At approximately what height above the surface must it be, assuming the orbit is circular? Hint: Use the period of the satellite's orbit and Kepler's third law of planetary motion. Use G = 6.67 x 10-11, and assume the mass of Earth is 5.98 x 1024 kg and its radius is 6.38 x 106 meters.

The plum pudding model of the atom state that ?

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 18oc and exits at 6.0 bar. the refrigerant undergoes a throttling process. determine the temperature, in oc, and the quality of the refrigerant at the exit of the expansion valve.

Arotating space station is said to create “artificial gravity”—a loosely-defined term used for an acceleration that would be crudely similar to gravity. the outer wall of the rotating space station would become a floor for the astronauts, and centripetal acceleration supplied by the floor would allow astronauts to exercise and maintain muscle and bone strength more naturally than in non-rotating space environments. if the space station is 200 m in diameter, what angular velocity would produce an “artificial gravity” of 9.80 m/s^{2} 2 at the rim?