QUES: Large brushes are desired for a larger brush contact area to maximize motor output, but small brushes are desired for low mass to maximize the speed at which the motor can run without the brushes excessively bouncing and sparking. (Small brushes are also desirable for lower cost.) Stiffer brush springs can also be used to make brushes of a given mass work at a higher speed, but at the cost of greater friction losses (lower efficiency) and accelerated brush and commutator wear. Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear.
Besides wear, what is a downside of stiff brush springs?

ANS: lower efficiency

QUES: Around the second century BC the first-known city-states emerged in central Myanmar. The city-states were founded as part of the southward migration by the Tibeto-Burman-speaking Pyu city-states, the earliest inhabitants of Myanmar of whom records are extant, from present-day Yunnan. The Pyu culture was heavily influenced by trade with India, importing Buddhism as well as other cultural, architectural and political concepts which would have an enduring influence on later Burmese culture and political organisation.
Were any of the early civilizations influenced by each other and if so by what how did it occur?

ANS: The Pyu culture was heavily influenced by trade with India

QUES: The University of Michigan shapes Ann Arbor's economy significantly. It employs about 30,000 workers, including about 12,000 in the medical center. Other employers are drawn to the area by the university's research and development money, and by its graduates. High tech, health services and biotechnology are other major components of the city's economy; numerous medical offices, laboratories, and associated companies are located in the city. Automobile manufacturers, such as General Motors and Visteon, also employ residents.
Name some automobile manufacturers in the city of Ann Arbor

ANS: General Motors and Visteon

QUES: In Suriname today, Dutch is the sole official language, and over 60 percent of the population speaks it as a mother tongue. Dutch is the obligatory medium of instruction in schools in Suriname, even for non-native speakers. A further twenty-four percent of the population speaks Dutch as a second language. Suriname gained its independence from the Netherlands in 1975 and has been an associate member of the Dutch Language Union since 2004. The lingua franca of Suriname, however, is Sranan Tongo, spoken natively by about a fifth of the population.
About what percentage of residents of Suriname speak Dutch?

ANS:
60