Q8 of 37 Page 13

The diameter of the wheels of a bus is 140cm. How many revolutions per minute must a wheel make to move at a speed of 66km per hour?


Diameter of a bus wheel = 140cm


∴ radius =


Distance covered in 1 revolution = Circumference of wheel


= 2πr


= 2 × π × 70


= 140π cm


Now, we find total distance covered


We know that,



Here, Speed = 66 km/hr


Time = 1 minutes



Putting a value in the formula, we get




⇒ Distance = 1.1 km


= 1.1 × 1000 m


= 1100 m


= 1100 × 100 cm


= 110000 cm


Now,





Number of revolutions = 250


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