Question

The strength of yarn decreases with the increase in specimen length due to more chances of the occurrence of \(\underline{\hspace{2cm}}\) places in longer specimen.

• A. Faults
• B. Strong
• C. Weak
• D. Very strong

Hint:

This is the "Weakest Link Effect": - A short chain might be lucky and have only strong links. - A very long chain is almost guaranteed to have at least one weak link somewhere. The chain (or yarn) always breaks at its weakest link, so longer yarns appear weaker on average when tested.

Answer 1

The Correct Option is C

Step 1: Understand the concept being described. This is known as the "weakest link theory" as it applies to textiles. A yarn is like a chain; its overall strength is determined by the strength of its weakest link. 
 

Step 2: Analyze the effect of specimen length. A yarn is never perfectly uniform; it has natural variations in thickness and strength along its length. It contains thin, weak places as well as thick, strong places. - A short specimen of yarn has a certain probability of containing a weak spot. - A longer specimen of yarn has a statistically higher probability of containing an even weaker spot somewhere along its greater length.

Step 3: Apply the weakest link theory. When the yarn is tested for strength, it will always break at its weakest point. Since a longer specimen is more likely to contain a very weak point than a shorter specimen, the average breaking strength measured for longer specimens will be lower than that for shorter specimens. 

Conclusion: The strength of yarn decreases with increasing specimen length because there is a higher probability of finding exceptionally weak places in a longer length.