Question

The diameter of a cycle wheel is $1.6m$. The wheel revolves $21$ times in one minute, then how much distance will the cycle cover in one hour:

• A. $3.636km$
• B. $6.336km$
• C. $6.633km$
• D. $2.640$

Answer 1

The correct option is B $6.336km$

$D=1.6m$
$r=\frac{1.6}{2}=0.8m$
$C=2\pi r$
$C=2\times \frac{22}{7}\times 0.8\Rightarrow C=5.028m$
in 1min$=21$ revolution
$\therefore$ in 1hr
$=21\times 60\times 5.028=6336m=6.336km$