NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 11: Area Related To Circles - Exercise 11.2
Question 5

Question. 5

Is it true that the distance travelled by a circular wheel of diameter \(d\) cm in one revolution is \(2\pi d\) cm? Why?

Answer:

false

Detailed Answer with Explanation:

Step 1: When a circular wheel makes one complete revolution, the distance it covers is equal to the circumference of the wheel.

Step 2: The formula for circumference is:

\( C = 2\pi r \)   or   \( C = \pi d \)

where \(r\) = radius of the wheel and \(d\) = diameter of the wheel.

Step 3: In SI units, if the diameter is given as \(d\) cm, we must first convert to metres (since SI unit of length is metre):

\( d\,\text{cm} = \dfrac{d}{100}\,\text{m} \).

Step 4: Substituting into the circumference formula:

\( C = \pi d \) (in cm)   or   \( C = \pi \times \dfrac{d}{100} \) m (in SI).

Step 5: The statement says distance = \(2\pi d\). But the correct formula is \(\pi d\).

Conclusion: Therefore, the given statement is False.

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 11: Area Related To Circles – Exercise 11.2 | Detailed Answers