Problem: Railway electrification system:

An early advantage of AC is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer can supply a range of voltages. Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery. More recently, the development of very high power semiconductors has caused the classic "universal" AC/DC motor to be largely replaced with the three-phase induction motor fed by a variable frequency drive, a special inverter that varies both frequency and voltage to control motor speed. These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation.

One taps on the transformer can supply what?
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A: unanswerable


Problem: Time:

The Vedas, the earliest texts on Indian philosophy and Hindu philosophy dating back to the late 2nd millennium BC, describe ancient Hindu cosmology, in which the universe goes through repeated cycles of creation, destruction and rebirth, with each cycle lasting 4,320 million years. Ancient Greek philosophers, including Parmenides and Heraclitus, wrote essays on the nature of time. Plato, in the Timaeus, identified time with the period of motion of the heavenly bodies. Aristotle, in Book IV of his Physica defined time as 'number of movement in respect of the before and after'.

What did Hundu cosmology identify time with?
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A: unanswerable


Problem: Gramophone record:

Over the years a variety of record equalization practices emerged and there was no industry standard. For example, in Europe recordings for years required playback with a bass turnover setting of 250–300 Hz and a treble roll-off at 10,000 Hz ranging from 0 to −5 dB or more. In the US there were more varied practices and a tendency to use higher bass turnover frequencies such as 500 Hz as well as a greater treble rolloff like −8.5 dB and even more to record generally higher modulation levels on the record.

In which country was the treble roll off greater?
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A: US


Problem: Brigham Young University:

The school broke off from the University of Deseret and became Brigham Young Academy, with classes commencing on January 3, 1876. Warren Dusenberry served as interim principal of the school for several months until April 1876 when Brigham Young's choice for principal arrived—a German immigrant named Karl Maeser. Under Maeser's direction the school educated many luminaries including future U.S. Supreme Court Justice George Sutherland and future U.S. Senator Reed Smoot among others. The school, however, did not become a university until the end of Benjamin Cluff, Jr's term at the helm of the institution. At that time, the school was also still privately supported by members of the community and was not absorbed and sponsored officially by the LDS Church until July 18, 1896. A series of odd managerial decisions by Cluff led to his demotion; however, in his last official act, he proposed to the Board that the Academy be named "Brigham Young University". The suggestion received a large amount of opposition, with many members of the Board saying that the school wasn't large enough to be a university, but the decision ultimately passed. One opponent to the decision, Anthon H. Lund, later said, "I hope their head will grow big enough for their hat."

Who served as interim principal until January 1876?
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A:
unanswerable