Strength of plant fibres

Question 1

Independant variable

Answer 1

source and type of fibre

Question 2

Dependant variable

Answer 2

mass that can be held

Question 3

Other variables to be controlled (2)

Answer 3

• Length of fibre

- Size of each individual mass

Question 4

Equipment required

Answer 4

• Stems of stinging nettles or celery
• bucket
• gloves
• paper towels
• clamp stands
• slotted masses and holders
• white tile
• sharp knife

Question 5

outline the method

Answer 5

plant material should be left to soak in a bucket of water for about a week in order for the fibres to be easily extracted (called retting). Or celery stalks should be left in beaker of coloured water in order for fibres to be easily seen and pulled out. Once fibres removed, connect between 2 clamp stands and gradually add mass in the middle until the fibre snaps. Try with individual fibres from different plants and different ways of combining fibres eg twists and plaits. Can also compare stem to individual fibres.

Question 6

Possible evaluation issues (4)

Answer 6

• Maintaining length of fibres
• Ensuring consistency when twisting or plaiting
• Using fibres of the same age (as they get older they become more brittle)
• Extracting whole fibres that are useful