Aim: The aim of my investigation is to find out if Hooke’s Law can be proved with a steal spring.
Equipment: Ruler, springs(x4), Base clamp, Weights (up 13N), boss clamp, goggles
* Pupils were not cramped together as they needed room to work.
* Goggles were worn to prevent eyes from getting damaged.
* People could not play with equipment.
* People could not run around in the science laboratory.
* Desks were cleared
There were not too many strict safety precautions used, as the only potential danger was if the spring snapped.
Prediction: My prediction is that Hooke’s Law can be proved through a steel spring, as if the weight on the spring will increase so will the extension. Hooke’s Law found that extension is proportional to the downward force acting on the spring. This tells me to find elastic limit when I am doing the experiment using the formula f=ke, which will give me the spring constant. I predict that the extension of the spring will be in steady steps up until the spring is stretched beyond the elastic limit. At that point the spring will have reached the point where Hooke’s law is no longer accurate. I will do enough experiments to find and exceed the elastic limit. I predict I will need to take about 12 measurements. I will record the spring’s extension in mm.
I predict the spring’s extension will increase in about 40mm each time, until the spring reaches its elastic limit. My predictions are based on Hooke’s Law, which basically says if you stretch something with a steadily increasing force, then the length will increase steadily too. I predict the results I gather are going to be reasonably reliable and accurate, also very close to the line of best fit. The key factors in my experiment are the weights and the spring. To get accurate results, I have to control these factors by putting on the weights gently on to the spring. Also not to vary the Newton weights, by adding them proportionally.
Method: My method of experimentation will be to use a clamp stand and boss clamp to suspend a spring from. A second boss clamp will hold in place a metre rule starting from the bottom of the spring to measure extension in mm. I will then add weights to the spring and measure extension. As I am doing this, I will record my results in a table. I will continue to do the tests until the spring will not return to its original shape. To make the tests fair I will use the spring with same number of coils and length, and same set of weights each time. Also I will add the weight proportionally in 1 Newton (100g) each time. Therefore the change in weight will remain the same.
Results: I am going to produce precise and reliable evidence by recording my results in a table and plotting a graph. I also hope to carry out the experiment 4 times and take an average to increase the reliability of my results, and instead of drawing 4 tables I have simply drawn an average table of results, which I have also used for drawing my graph.
I used all the equipment safely, following all of the safety rules and observing the experiment entirely.
My results are meaningful as they support my objective. I placed them in a table to make them easier to identify. I did not need to take repeat readings, as I found them reliable and accurate when I noticed that the spring started to follow a pattern as the spring’s extension increased.
Here is my table:
Number of Newton’s added
Length of the spring (mm)
Extension of spring
I used all the apparatus with the skill and precision to achieve the accurate results. I took 12 results, which I felt to be the appropriate number, as 11N is where the elastic limit occurred and I wanted to find out what happened when I went beyond.
On the next page I have drawn the graph of these results with the line of best fit.
Analysis: The results I have gathered are reasonably reliable and accurate. The experiment graph shows that all of the results were very close to the line of best fit. This shows that my results for this test support Hooke’s Law well, which proves my prediction to be correct. In conclusion I am pleased with my results and feel they support each other as well as the laws they were based on.
The principle of Hooke’s Law can be seen in a graph of spring extension. From my results I can see that as load increases so does extension of a spring.
I noticed a Pattern in my results, for the first 5N, the spring’s extension increased about 40mm on each Newton added. However it occurred to me as the extension increased the difference between results rose slightly, this could be as the spring was nearing its limit of proportionality.
11N on the graph shows that the limit of proportionality has been reached; this is where Hooke’s law is no longer accurate. This point is the spring’s elastic limit, if the force is removed from the spring it will no longer return to its original shape. Beyond this point the atoms in the spring’s material begin to break their bonds until eventually the spring yields and breaks. This shows that Hookes Law does have a limit, as does a spring and does have limitations and if kept within these boundaries will provide reliable accurate results.
I added the Newton’s proportionally, 1 Newton at a time, as I could observe the extension pattern and understand Hooke’s Law better. Also it demonstrates that Extension is proportional to the load. My prediction is accurate as I said Hooke’s Law could be proved through a steel spring, which was shown in my results.
Evaluation: I am happy with the method I used and I think it was a precise and simple way of finding my objective. I found my results accurate as they followed a general pattern (increasing in the same amount). I found few results misleading as the results increased in larger amounts, but that might have been because the spring was reaching its elastic limit. If the experiment were to be carried out again, changes could be made to reduce experimental error. A pointer on the spring would help in gathering the information more accurately.
However, my results are reasonably reliable as all of them were very close to the line of best fit. I do consider my results good enough evidence to support my conclusion as most of them followed a steady pattern and showed that if you stretch something with a steadily increasing force, then the length will increase steadily too. Some of my results were anomalous as when they were approaching the elastic limit the results started increasing in different amounts. If I would carry on with my experimentation, I would find out what happened after the limit of proportionality had been reached using Hookeï¿½s law, achieving results until the spring became straight and eventually breaking. However the change in length at this stage is very small and special measuring equipment would be needed in order to conduct a reasonable experiment.