- Level: GCSE
- Subject: Design & Technology
- Word count: 2426
Stretching Materials
Extracts from this document...
Introduction
Stretching Materials Planning My Work For this experiment I will need to investigate the factors that effect the 'stretch' or extension of a piece of material. Aim: To find a relationship between the length a piece of material can stretch under a certain weight, and how a certain length effects how much it stretches. The extension of the materials I use will rely on whether the molecules are strong enough to hold a definite shape. In a solid there are two forces acting. There are attractive forces if molecules try to move apart and repulsive forces if molecules try to move closer. If the material is stretched then the forces are unbalanced. This is what is taking place in our experiment. We will want to investigate the stretch of our materials and so it is important to bare in mind this information to identify the key factors that might affect the extension of the material. From this information we can predict that the weight we apply to our material will effect its extension by adding to the downward force acting on the material. However the properties of the material we use will also vary its extension by the individual structure of the molecules in each material. To reach our aim we will also carry out a set of experiments, again with the different materials, where the length of the material is varied. ...read more.
Middle
My results are then a lot easier to handle. Analysing My Evidence With the data I had collected, I decided to create scatter graphs to show even more clearly the information. To my points, I added a line of best fit in order to show the trends and patterns. I did two separate graphs for each experiment as they were holding deferent information, but showed the results for the string and elastic on the graphs together to show how they compare to each other. These graphs can be seen on the next pages on the graph paper. I am first going to look at the graph for experiment one where the variation is the weight. We can see that there is a clear pattern of increase in the extension. We can see that with the elastic, at first there is a sharp increase where the extension is directly proportional to the stretching force, and is shown by a straight line through the graph. This means that the same amount of weight added is equal to the same extension of the material, and is called Hooke's Law. In this experiment, up to 2N, the elastic gives an equal extension to an equal weight and obeys Hooke's Law. The 2N point is the elastic limit, and past this point the elastic acted differently and did not obey Hooke's law. ...read more.
Conclusion
Looking at the graph for experiment one, you can see that the points follow an almost exact line showing that the experiment was carried out accurately. However, it is also interesting to see the graph for experiment two, and how many points on the graph do not follow the line of best fit and the points are slightly more randomly placed. It shows how this experiment produced less correct results to the first. This indicates that perhaps the experiment needed to be carried out more accurately as there at least two worryingly out of place, anomalous results. These points would need to be repeated. Seeing as it was the second experiment only that needed more accuracy, I looked into different ways of improving the results. When we were previously carrying out the experiment, we had attached the material by tying it to each end. This perhaps was unwise and it is easy to imaging that the more of the material than wise is used up in the knot, rather than as the length. Creating loops may improve the results to give them a more regular pattern and make them more reliable. It is obvious however, that even with these stray results, they can still successfully support a firm conclusion, and would be even more supporting is the few odd readings were repeated. I could also add additional evidence to the conclusion and extend the inquiry by looking more closely at the molecular structure of additional materials to widen my range of information. ...read more.
This student written piece of work is one of many that can be found in our GCSE Resistant Materials section.
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