<PRE><B>Question 467534</B>
an automobile tire is 30 inches in diameter. How fast (rpm) does the wheel turn on the axle when the automobile maintains a speed of 45 mph?
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Circumference of the wheel = 30pi inches = (30/12)pi = 2.5pi ft
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At 45 mph the wheel covers 45*5280 ft in an hour
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revolutions per hour = (45*5280/2.5pi)
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rpm = (45*5280/60*2.5pi) = 504.20
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Cheers,
Stan H.

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