Question

A bicycle wheel makes 500 revolutions in moving 1 km. Find the diameter of the wheel.

Answer 1

A bicycle wheel makes 500 revolutions in moving 1 km
In 1 revolution, the bicycle wheel covers
$=\frac{1}{500}km=\frac{1000}{500}m=2m$ [$\because$ 1 km = 1000m]
1 revolution distance = Circumference of the wheel
$\Rightarrow 2\pi r=2\Rightarrow 2\times \frac{22}{7}\times r=2$
$\Rightarrow r=\frac{2\times 7}{2\times 22}=\frac{7}{22}$ [$\because$ circumference of a circle $=2\pi r$]
$\therefore$ Diameter (d) $=2r=\frac{7}{22}\times 2=\frac{7}{11}=0.636m$