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Question
The speed of a car is 66km per hour. If each wheel of the car is 140cm in diameter, find the number if revolution made by each wheel per minute.
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Solution
The Circumference of Circle with diameter d is πd
The Circumference of a Circle with diameter 140cm is π x 140
= `(22)/(7) xx 140`
= 440cm
distance moved in 1 hour
= 66km
= 6600000cm
distance moved in 1 minute
= `(6600000"cm")/(60)`
= 110000cm
Number of revolutions
= `"Total distance moved"/"Circumference of Circle"`
= `(110000)/(440)`
= 250.
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