Part 2
P3 estimate the purity of samples using scientific techniques P4 use instruments/sensors to test substances or materials.
M3 justify the choice of instruments in the practical exercises.
This document is to be used as a guideline only, it has been signed off by my teacher as passed.
WARNI...
Testing tenslee strengt of celng fem
Background info-
Tensile strength: maximum load that a material can support without breaking.
Met od:
1. Set up two clamps and clamp stands opposite each other.
2. Attach each end o the clinga film strips at the clamps.
3. Gradually add masses to the middle o the strip and record how much mass is
required in order to tear the strip.
4. Calculate the breakinga stress.
Area of strlp ln cm Mass at breaklng Force (N) Caecueated stress
polnt (F/A)
300 980ga 9.6 0.032
600 1,780ga 17.44 0.029
900 3,020ga 29.60 0.032
Resuets:
Conceuslon and Evaeuation:
The calculated stress increases as the area increases. A gareater orce was needed to
break a largaer area o the clinga film. The way we improved the accuracy o the experiment
was by addinga smaller masses o 10ga when we knew the clinga film was almost at its breakinga
point. To improve the investgaaton, we could investgaate diferent brands o clinga film,
notnga down whether the quality and strengath o clinga film varies between diferent
manu acturers.
Also, another way in which the experiment completed could be improved, is that we could
do repeats which would make our results more reliable. We could also use a more precise
ruler when measuringa the lengaths o the clinga film strips.
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