Tensile strength - plan
Plant are able to deal with great amounts of exerted forces due to their high tensile strengths (resulting from its turgid cell wall and sclerenchyma cells). Tensile strength is defined as the maximum stress caused by a pulling force a material can withstand without breaking (failing). (1)
In this investigation, I will be looking at the effects of pulling force on several different plant fibres- Coir (fibres from husk of coconuts), fibres from the stem of a stinging nettle, fibres from the stem of a flax plant and the fibres from the leaves of a type of bananas. I will decide which fibre has the highest tensile strength depending on which could withstand the greatest amount of force (N). I decided to measure the tensile strength force because it a measurement which can be easily compared hence my findings will be quite easy to understand
I will use these results to come to a conclusion on whether the strength of the stem is entirely due to the fibres or whether the packing tissues and epidermis are the major contributors
I predict that the fibre from the flax plant (2) will be able to withstand the most force (double the amount that the fibre from the banana plant will be able to withstand and hence have the highest tensile strength.
1. Tie hair back, wear googles and a lab coat which can button up
2. Fill a bowl with cold water
3. discard any leaves and flowers from the stem of the mature stinging nettle and fully submerge the stem in the bowl of water
4. Leave the stems to be soaked outside for at least a week
5. Once you remove the stems from the water, wash them in order to rid of any of the softened tissue then dry the remaining fibres with paper towels
6. Peel away the fibres from the central pith and discard the pith leaving only the peeled fibres
1. Make loops on both ends of the fibre so that one end can be attached the spring balance and the other on the loads hook
2. Hook the spring balance to the clamp of the retort stand and attach the fibre to the spring balance
3. Slowly attach the loads hook to the other end of the fibre (making sure that it can withstand the weight)
4. Adjust the spring balance reading until it returns back to 0N
5. Put a piece of load with mass 2g on the hook
6. Keep adding load gradually until the fibre snaps. Record the Newtons at the point of breakage
7. Repeat step 1-6 using fibres from the same source 2 more times
8. Repeat step 1-7 using fibres from the other 3 sources
Plant fibres- (coir, fibres from stem of stinging nettle, fibres from flax plant, fibres from leaves of banana)
My independent variable, a range of different fibres to compare tensile strengths and see which one has the greatest. A wide range improves validity of experiment
to soak Stems in. easy to carry and move.
To measure out the water. Using a 100ml beaker as oppose to a beaker with no measurements so...