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Question
The wheels of the locomotive of a train are 2.1 m in radius. They make 75 revolutions in one minute.
Solution
Radius of the wheel = 2.1 m
Circumference of the wheel = 2πr
`=2xx22/7xx2.1`
= 13.2 m
Distance covered by the wheel in 1 revolution = 13.2 m
Distance covered by the wheel in 75 revolutions `=(13.2xx75)=(990xx1/100)"m" `
`=(990xx1/1000) "km"`
Distance covered by the wheel in 1 minute = Distance covered by the wheel in 75 revolutions `= 990/1000 "km"`
∴ Distance covered by the wheel in 1 hour `=990/1000xx60`
= 59.4 km / h
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