Problem: Guinea-Bissau is bordered by Senegal to the north and Guinea to the south and east, with the Atlantic Ocean to its west. It lies mostly between latitudes 11° and 13°N (a small area is south of 11°), and longitudes 13° and 17°W.
What longitudes does Guinea-Bissau mostly lie between?
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Answer: 13° and 17°W


Problem: Currents induced into this winding provide the rotor magnetic field. The shape of the rotor bars determines the speed-torque characteristics. At low speeds, the current induced in the squirrel cage is nearly at line frequency and tends to be in the outer parts of the rotor cage. As the motor accelerates, the slip frequency becomes lower, and more current is in the interior of the winding. By shaping the bars to change the resistance of the winding portions in the interior and outer parts of the cage, effectively a variable resistance is inserted in the rotor circuit. However, the majority of such motors have uniform bars.
Not changing the shapes of the bars creates what?
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Answer: unanswerable


Problem: Railways must operate at variable speeds. Until the mid 1980s this was only practical with the brush-type DC motor, although such DC can be supplied from an AC catenary via on-board electric power conversion. Since such conversion was not well developed in the late 19th century and early 20th century, most early electrified railways used DC and many still do, particularly rapid transit (subways) and trams. Speed was controlled by connecting the traction motors in various series-parallel combinations, by varying the traction motors' fields, and by inserting and removing starting resistances to limit motor current.
What is speed limit for railways?
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Answer:
variable speeds