Question

The diameter of the wheel of a bus is $140cm$. How many revolution per minute must the wheel make in order to move at a speed of $66km/hr$.

Answer 1

Diameter of the wheel $=140cm$

Radius $=70cm$

Now,

$1$ round distance $=2\pi r=2\times \frac{22}{7}\times 70=440cm$

Since distance traveled in $60mnts=66\times 1000\times 100cm$

Therefore, distance traveled in $1mnts=\frac{66}{60}\times 1000\times 100cm=110000cm$

Revolution in $1mnt=\frac{110000}{440}=250$

Hence, $250$ revolution per minute must the wheel make in order to move at a speed of $66km/hr.$