Question
Give an activity to show that twisting of fibres into yarn increases the strength of fibres.
Solution
Procedure :
1. Take a 15-20 cm long loose strand of cotton fibre. Break it into two parts of nearly equal size. Twist one part of it to make a thread. Let the other piece be as such.
2. Hold the untwisted part and apply a pull on its both the ends till it breaks.
3. Repeat the same with the twisted part till it breaks.
4. Compare the pull required to break the twisted and the untwisted thread.
Observation :
Greater force (or pull) is required to break the twisted thread than the untwisted thread.
Inference :
Twisting of fibres into yarn (or thread) increases the strength of the fibres.
