# I am doing an investigation in to how much a metre rule bends when one end is clamped to a table and a varied load is attached to the other end that hangs off the table, thus bending the rule.

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Introduction

Tom Owens

Set 5

Physics Sc1

The Plan:

Simple procedure:

I am doing an investigation in to how much a metre rule bends when one end is clamped to a table and a varied load is attached to the other end that hangs off the table, thus bending the rule. I shall take relevant readings that I shall repeat three times and record the results in a table.

Hypothesis:

I hypothesise that the greater the load attached to the metre rule, the more the metre rule will be inclined to bend. There are two reasons for this. The first is because ‘the extension is directly proportional to the stretching force.’ This is Hooke’s Law but cannot only be applied to springs, but also to metal wires, girders in bridges, but more importantly anything where the extension will be affected by the load. To see if my prediction is correct I will experiment, and obtain results using Hooke’s Law.He found that the extension is proportional to the downward force acting on the spring.The formula that represents that is:. This is where F = force in Newton’s, k = spring constant and x = extension in metres. I also believe that the amount that my metre rule will bend shall be quantitative. By this I mean that if the load doubles, so will the extension. I believe that if I put on three times the load, I will get three times the extension (and so on until eventually the metre rule cannot hold any more weights and snaps.) This shows that the extension is directly proportional to the stretching force. Therefore I will choose the following loads: 100g, 200g, 300g, 400g, 500g, 600g, 700g, 800g, 900g, and 1000g.

Middle

Variables:

The manipulated variable, which I identified, will be the weight of the load. This variable will constantly change so that I can see how much the rule bends with a different mass on it each time. The results (which I shall repeat in order to create a fair test and identify any anomalies which I can later repeat) can then be recorded in a table, which can then be converted in to graphs. I hope that by repeating my readings, I can further prove that my hypothesis will hopefully be correct. Repeat readings will also enable me to work out the averages of my readings and in so doing create more accurate graphs.

The dependent variable will be the length of metre rule that hangs over the table. This shall remain constant throughout the experiment. I shall have 20cm of the rule on the table and 80cm of the rule hanging off the table. Otherwise, if we altered the load and the length of the rule hanging over the table we would not have a fair test as we could not claim that load is directly proportional to the extension because as the metre rule would hang at different lengths over the table, the extension would vary even with the same load on the rule. This would flaw the experiment, as there would be no point in investigating how extension varies with load if we could not tell due to the fact that the rule was hanging at different lengths over the table. I shall control the length of the metre rule over the table by clamping one end to a table with a G-clamp, thus knowing it can’t alter and keeping this variable the same throughout the experiment.

I identified two other variables.

Conclusion

The only other further work I could have done to provide additional and relevant evidence would have been to ensure that my hypothesis was proved correct by taking a greater range of evidence e.g. a greater range of masses to add to the metre rule. This would have allowed me to create more relevant and correct readings that could have gone towards backing up my hypothesis. Any anomalies would have been more easily identified and I would have created a greater range of results. Also, I could have had different amounts of the rule on the table e.g. 30cm on the table and 70cm hanging off the table. This would have enabled me to compare the repeated results to see if the same theory emerged and to prove that it was not a fluke. It would not matter that the extensions differed, provided the theory still remained the same. This was however unnecessary as I have repeated my readings enough times, so that one theory stood up above them all, to eventually prove my hypothesis thoroughly correct.

(3593 words)

Acknowledgements:

Physics For You - pages 114 and 74

The Internet – www.studentcentral.co.uk

Longman’s Student Revision Guide

This student written piece of work is one of many that can be found in our AS and A Level Waves & Cosmology section.

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