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The speed of the car is 66 km/hour. If each wheel of the car is 140 cm in diameter, find the number of revolutions made by each wheel per minute.

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#### Solution

Circumference = 2 π r = π d

`= 22/7 xx 140`

= 440 cm = 4.4 m

Circumference= 4.4 m

Distance travelled in one hour= 66k m = 66000 m

Distance travelled in one minute = `66000/60 = 1100 "m"`

No. of revolutions in one minute= `"Distance"/"Circumference"`

= `1100/4.4`

= 250

No. of revolutions made by each wheel = 250 rpm.

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