Question

A disc of radius R rolls on a rough horizontal surface the distance covered by the point A in one revolution is:

• A. $2\pi R$
• B. $2R$
• C. $8R$
• D. $\pi R$

Answer 1

The correct option is A $2\pi R$

In one revolution the total distance covered by the disc is whole of its circumference. When one revolution has completed. The particle on the disc comes back to its original position.

Therefore the distance covered is $2\pi r$