The wheels of a car are of diameter $80\ cm$ each. How many complete revolutions does each wheel make in $10\ minutes$ when the car is travelling at a speed of $66$ km per hour?

Given: The wheels of a car are of diameter $80\ cm$ each. The car is travelling at a speed of $66$ km per hour in $10$ minutes.

To do: To find the number of revolution completed by the wheel in $10$ minutes.

Solution:

As given, diameter of the wheel$=80\ cm$

$\therefore$ Radius of the wheel $r=\frac{Diameter}{2}=\frac{80}{2}=40\ cm$

Circumference of the wheel$=2\pi r=2\times\frac{22}{7}\times40=251.42\ cm=2.51\ m$

Speed of the car$=66\ km/h$

Time to travel by the car$=10$ minutes$=\frac{10}{60}=\frac{1}{6}$ hour

$\therefore$ Distance travelled by the car$=speed\times time=66\times\frac{1}{6}=11\ km=11000\ m$

Let $n$ be the number of revolutions completed by the wheel in $10$ minutes.

$\therefore n\times2.51=11000$

$\Rightarrow n=\frac{11000}{2.51}=4375.49$

Thus, each wheel will make around $4375$ revolutions in $10$ minutes.
 

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Updated on: 10-Oct-2022

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