Find the revolution per minute is required for the bus wheel with the diameter of 140 cm to make in order to keep a speed of 66kmph.
Option:
A. 125
B. 250
C. 400
D. 800
Answer: B . 250
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Justification:
The bus speed S = 66 kmph = > S = 66 / 60 = 1.1 kmpm => S = 1100 meter per minute
The Perimeter of the bus wheel P = 2 * (22/7) * 70 = 440 cm.
Bus wheel covers 440 cm in one revolution => Number of revolution per minute = 1100 meter / 440 cm
=> N = 1100 * 100 / 440 = 250
