Question

The wheel of a motor cycle is of radius 35 cm. How many revolution per minute must the wheel make, so as to keep a speed of 66 km/h?

• A. 400
• B. 500
• C. 600
• D. 650

Answer 1

The correct option is B 500

Given, radius of wheel, r = 35 cm.

Circumference of the wheel $=2\pi r$
$=2\times \frac{22}{7}\times 35$
= 220 cm

But speed of the wheel $=66km{h}^{-1}=\frac{66\times 1000}{60}m/min$

$=1100\times 100cmmi{n}^{-1}$

$=110000cmmi{n}^{-1}$

$\therefore$ Number of the revolution in min $=\frac{110000}{220}=500revolutions$

Hence, required number of revolutions per minute is 500.