Measurement Of Length - Curved Surface

• The length of a curved surface cannot be measured using a scale.
• We can measure the length of a curved surface by using a thread

Example - 

1. Measure a curved line AB with the help of a thread.
2. Put a knot on the thread near one of its ends, place this knot at point A
3. Keep moving the thread along its line by using your fingers and thumb.
4. Use this process till the other end B is reached
5. Mark the ends of the thread A and B
6. Now, stretch the thread along a metre scale
7. Measure the length from beginning to the final mark
8. We get the length of the curved surface.