Context and question: Most electrification systems use overhead wires, but third rail is an option up to about 1,200 V. Third rail systems exclusively use DC distribution. The use of AC is not feasible because the dimensions of a third rail are physically very large compared with the skin depth that the alternating current penetrates to (0.3 millimetres or 0.012 inches) in a steel rail). This effect makes the resistance per unit length unacceptably high compared with the use of DC. Third rail is more compact than overhead wires and can be used in smaller-diameter tunnels, an important factor for subway systems.
What is more prefferable for subway lines?
Answer: Third rail
Context and question: Through its program of need-based financial aid, Yale commits to meet the full demonstrated financial need of all applicants. Most financial aid is in the form of grants and scholarships that do not need to be paid back to the university, and the average need-based aid grant for the Class of 2017 was $46,395. 15% of Yale College students are expected to have no parental contribution, and about 50% receive some form of financial aid. About 16% of the Class of 2013 had some form of student loan debt at graduation, with an average debt of $13,000 among borrowers.
How is most financial aid obtained at Yale?
Answer: grants and scholarships
Context and question: A number of vessels visiting the islands were attacked and their crews killed. In 1834, Captain DonSette and his crew were killed. Similarly, in 1845 the schooner Naiad punished a native for stealing with such violence that the natives attacked the ship. Later that year a whaler's boat crew were killed. In 1852 the San Francisco-based ships Glencoe and Sea Nymph were attacked and everyone aboard except for one crew member were killed. The violence was usually attributed as a response to the ill treatment of the natives in response to petty theft, which was a common practice. In 1857, two missionaries successfully settled on Ebon, living among the natives through at least 1870.:3
Out of what city was the Sea Nymph sailing?
Answer:
San Francisco