Question

The diameter of a bicycle wheel is 28cm. what distance will it cover in 100 revolutions?

Answer 1

Hint:
Here they have taken the wheel of the bicycle. This is circular in shape. Wheel of the bicycle will rotate to make the revolutions. Means that circle is going to cover the distance.

Complete step by step solution:
Here given that diameter of the wheel is 28cm.
Now when the wheel will rotate it will cover some distance definitely.
But in this case, we can say at perfect that it is the rim of the wheel that is covering the distance.
Observe the following figure.

When we open a circle we get a straight line. And here the line itself is covering the distance.
It is nothing but the circumference of the circle.
Now,
 Circumference of the circle= \[2\pi r\]
                    \[
   \Rightarrow 2\pi \dfrac{D}{2} \\
   \Rightarrow 2 \times \dfrac{{22}}{7} \times \dfrac{{28}}{2} \\
   \Rightarrow 22 \times 4 \\
   \Rightarrow 88cm \\
\]
This is the distance covered by the wheel in one revolution.
Now to find the distance in 100 revolutions multiplies above distance by 100.
Distance covered in 100 revolutions = \[88 \times 100\]
                           \[ \Rightarrow 8800cm\].

Thus the distance covered by the wheel of the bicycle in 100 revolutions is 8800cm.

Note:
1) First, find the distance covered in one revolution that will make the work easy.
2) No need to find the area of the wheel.
3) Here remember only in case of circle or wheel distance covered is the circumference of the circle.