Question

The number of revolutions made by a circular wheel of radius 0.25 m in rolling a distance of 11 km is ______.

Options

• 2800

• 4000

• 5500

• 7000

Answer 1

The number of revolutions made by a circular wheel of radius 0.25 m in rolling a distance of 11 km is 7000.

Explanation:

Here,

Number of revolutions = ${\displaystyle \frac{\text{Total distance}}{\text{Distance covered in} 1 \text{revolution}}}$

Given,

Radius = 0.25 m

Total Distance = 11 km = 11,000 m

Therefore,

Distance covered in one revolution = Circumference of wheel

= 2πr

= ${\displaystyle 2\times \frac{22}{7}\times 0.25}$

= ${\displaystyle 2\times \frac{22}{7}\times \frac{1}{4}}$

= ${\displaystyle \frac{11}{7}}$ m

Now,

Number of revolutions = ${\displaystyle \frac{\text{Total distance}}{\text{Distance covered in} 1 \text{revolution}}}$

= ${\displaystyle \frac{11000}{\frac{11}{7}}}$

= ${\displaystyle 11000\times \frac{7}{11}}$

= 1000 × 7

= 7000