Question

The diameter of the wheel of a car is $70cm$. How many revolutions will it make to travel $1.65km$?

Answer 1

Let the radius of the wheel be $\left(r\right)$

Diameter of the wheel$=70cm$

$\Rightarrow r=\frac{70}{2}cm=35cm$

Circumference of the wheel $=2\pi r$

$=2\times \frac{22}{7}\times 35cm$

$=2\times 22\times 5cm$

$=220cm$

In one revolution, the wheel covers the distance equal to its circumference.

.$\Rightarrow 220cm$ distance $=1$ revolution

$\Rightarrow 1cm$ distance $=\frac{1}{220}$ revolutions ---(1)

Since, $1km=100000cm$

$\Rightarrow 1.65km=1.65\times 100000cm=165000cm$

$\Rightarrow 165000cm=\frac{1}{220}\times 165000$ revolutions

$\Rightarrow 165000cm=750$ revolutions

Thus, the wheel will make $750$ revolutions to travel $1.65km$.