Question

A wheel has diameter $84cm$. Find how many complete revolutions must it take to cover $792meters$

Answer 1

Let $r$ be the radius of the wheel

Diameter $=84cm$

$$\begin{gathered} 2r=84 \\ r=\frac{84}{2} \\ r=42cm \end{gathered}$$

Circumference of the wheel $=2\pi r$

$$\begin{gathered} =2\times \frac{22}{7}\times 42 \\ =264cm \\ =2.64m\left[\because 1cm=\frac{1}{100}m\right] \end{gathered}$$

So, the wheel covers $2.64meters$ in one complete revolution .

Total number of revolutions in covering $792meters=\frac{729}{2.64}$

$=300$

Therefore, the wheel takes $300$ revolutions to cover $792meters.$