Hooke's Law - Stretching springs
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Y7: An experiment to investigate the stretching of springs
Recording ResultsThe results were recorded in a table. It is important to record all of the readings taken and to show clearly any calculations we do from those readings. We therefore needed four columns.
w = m g where g = gravitational field strength of Earth = 10 N/kg As 'g' is given in N/kg we had to change the mass in grammes into a mass in kilograms before we could calculate the weight in newtons.
Results table (one was needed for each set of results)A graph was plotted of the weight added to the hanger against the extension of the spring. The points of both sets of results were plotted on the one graph. This gave us a scatter graph of the results. It showed us not only the trend of the results but also how precise our readings were. A key explaining 'which set was which' was written on the graph. The title of the graph indicated what the experiment involved - it did not just say what was plotted angainst what - that could be seen from the labelling of the axes! Anomalous results were plotted, circled and repeated. A best fit line was plotted. These points indicated a trend of proportionality so a smooth straight line was drawn. It did not matter wherther it went through all of the points. What mattered was that it showed the general pattern that the results indicated.
ConclusionThe amount the spring stretches plotted against the weight added to the hanger gives a straight line that goes through the origin. This means that the extension of a spring is directly proportional to the stretching force applied to it.. Hooke's Law states that the extension of a spring is directly proportional to the applied load (providing the elastic limit has not been exceeded)
At A level we express the idea in an equation:We can put this in an equation. The constant 'k' shows it is a proportional relationship:Click here to go to the page on springs in combination - springs in series and parallel Also see Simple Harmonic Motion Try this puzzle its educational and fun! |
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