The diameter of a cycle wheel is 21 cm. How many revolutions will it make in moving 66 m ?

Answer

To solve the problem, we need to determine how many revolutions a cycle wheel with a diameter of 21 cm will make when it travels a distance of 66 meters.

### Step-by-Step Solution:

**Step 1: Convert the distance from meters to centimeters.**
- Since the diameter is given in centimeters, we should convert the distance from meters to centimeters.
- 1 meter = 100 centimeters.
- Therefore, 66 meters = 66 × 100 = 6600 cm.

**Step 2: Calculate the circumference of the cycle wheel.**
- The formula for the circumference (C) of a circle is given by:
\[ C = \pi \times d \]
where \(d\) is the diameter.
- Given that the diameter of the cycle wheel is 21 cm:
\[ C = \pi \times 21 \approx 3.14 \times 21 \approx 66 cm. \]

**Step 3: Calculate the number of revolutions.**
- The number of revolutions made by the wheel can be calculated using the formula:
\[ \text{Number of Revolutions} = \frac{\text{Total Distance}}{\text{Circumference}} \]
- Substituting the values we have:
\[ \text{Number of Revolutions} = \frac{6600 \text{ cm}}{66 \text{ cm}} = 100. \]

### Final Answer:
The cycle wheel will make **100 revolutions** in moving 66 meters.