A car travels 1 kilometre distance in which each wheel makes 450 complete revolutions. Find the radius of the its wheels.
Let the radius of wheel be r. Thus, circumference C of the wheel
$C=2 \pi r$
Since car travels 1 km distance in which wheel makes 450 complete revolutions. Then
The distance covered by wheel in one revolution $=\frac{\text { Distance moved }}{\text { Number of revolution }}$
$=\frac{1000 \mathrm{~m}}{450}$
$=\frac{20}{9} \mathrm{~m}$
We know that,
The distance covered in one revolution $=$ circumference of the wheel
$\frac{20}{9}=2 \times \frac{22}{7} \times r$
$r=\frac{20 \times 7}{9 \times 2 \times 22}$
$=0 . \overline{35} \mathrm{~m}$
$=35.35 \mathrm{~cm}$
Hence the radius of wheel is $35.35 \mathrm{~cm}$.
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