1. Circumference of circle Application

2. Circumference of circle Application - Introduction
We know that perimeter is measuring the outside of any shape.
Let us learn how to calculate perimeter by small Illustration of using rope length.
Let us take a rope of x length and try reshaping the rope into a square as given below.
X length
From this, its clearly seen that Perimeter of a square = length of the rope.

3. Circumference of circle Application - Introduction
Now let us see 2nd illustration for Circle:
Let us take the same rope of x length and try reshaping it as a circle.
X length
What can you conclude from the illustration?
From the above illustration, we conclude that Circumference of a circle = length of the rope.
Therefore, if the rope of any particular length is reshaped into any shape , can become perimeter of that shape
(as far as circle, its circumference)

4. Revolution
If a bicycle has covered some distance with certain number of revolutions, we have following formulas
Formula to find
Distance travelled = Circumference x Number of revolutions

5. So, to convert cm to m, we divide the 3960 by 100
Example 2: The diameter of a bicycle wheel is 63 cm. How much distance will it cover in 20 revolutions? Solution Given : d= 63 , no. of revolution = 20 Distance travelled = Number of revolutions X Circumference Step1: Finding Circumference Distance covered in one rotation = Circumference of wheel Circumference of the wheel = πd =22 x 9 = 198 cm Therefore, Distance covered in one rotation = 198cm Step 2: Finding Distance for 20 revolution We know that, Distance travelled = Number of revolutions X Circumference Distance travelled in 20 revolutions = 20 X 198 cm = 3960 cm = 39m 60cm (Ans) 9
Divide 63 and 7 by 9
We know that 1m = 100cm,
So, to convert cm to m, we divide the 3960 by 100
3960cm = 39m 60cm

6. Step1: Finding Circumference
Example 3: A scooter wheel makes 50 revolutions to cover a distance of 8800 cm. Find the radius of the wheel.
Solutions: Given : revolution=50 , distance=8800cm To Find: radius of wheel
Step1: Finding Circumference
We know that, Distance travelled = Number of revolutions X Circumference
= 50 x Circumference
Circumference = 176 cm
Step2: Finding radius
We know that, Circumference = 2πr 4 16
Divide 176 and 44 by 11 4
Divide 16 and 4 by 4
r= 4 x 7 = 28 cm (Ans)

7. Solution: Given: radius=70cm distance = 132m To Find : revolution
Example 4 : The radius of a cart wheel is 70 cm. How many revolution does it make in travelling a distance of 132 m.
Solution: Given: radius=70cm distance = 132m To Find : revolution
Step1: Finding Circumference
We know that, Circumference = 2πr 10
Divide 70 and 7 by 7
Circumference = 2 x 22 x 10 = 440cm
Step 2: Finding number of revolution
Distance travelled = Number of revolutions X Circumference
13200 = Number of revolutions X 440
We know that 1m = 100cm,
So, to convert m to cm, we
multiply 132m as cm
132m = 132 x 100 = 13200cm
1200 30
Divide and 440 by 11 40
Divide 1200 and 40 by 40
Number of revolutions = 30 (Ans)

8. Try these
1. A scooter wheel makes 50 revolutions to cover a distance of 2200 cm. Find the radius of the wheel. 2. The radius of a bus wheel is 28 cm. How many revolution does it make in travelling a distance of 88 m.