Investigate the way in which springs arranged in parallel (i.e. side by side) behave when a fixed load (force) is applied to them. Explain how the increasing the number of springs affect the behaviour.

Test for the weight of the load

        The load that I will use will not deform two springs and will stretch the springs a long distance from its original position.

Conclusion from tests

        I will use a total of seven springs for each test and a load of 500g. I chose 500g because 600g comes very close to wrecking the springs and eight springs gave almost the same reading as seven springs. 400g was a good option but 500g definitely pulled the springs closer to their limit.  

Apparatus:

• Clamp stand
• Springs
• Weights
• Ruler
• Play-doh
• Metal rods

Variables:

• Width (or size) of the springs
• Number of springs
• Weight of load
• Weight of metal rod
• Amount of play-doh used

Experimental Variable:

        The only variable that will be used in this investigation is the number of springs. The rest of the variables will be controlled in order to keep it a fair test.

Fair Test:

        Only the number of springs will vary. The rest of the variables will be controlled. The following methods will be used to control the variables:

• Springs will all be of the same size and shape
• The load will not change, the same load will be used for all the
• The same piece of play-doh will be used to secure the load and springs

              

This will be done because the weight of the play-doh will definitely have an effect on the behavior of the springs. It is a small effect but very significant.

Method:

1. Set up the experiment as shown in the diagram.

2. Start by putting 2 springs onto the clamped metal rod.
3. Put another metal rod on the other ends of the springs.
4. Secure both rods by adding a piece of play-doh on either side.
5. Add the load onto the lower metal rod.
6. Calculate the extension: Extension = New length – Original length 
7. Record results then repeat procedure using more springs.
8. Tabulate results.

Safety:

        In order to keep this experiment a safe one, I have checked with the teacher. Play-doh will be attached to the sides of the metal rods to prevent the springs and load from slipping off.

Measurement:

        I will be measuring the extension of the springs with a ruler using centimeters as my unit of measurement. I will do this by first measuring the distance from the lower metal rod (without the load) to the edge of the table. Then, I will measure the distance from the lower rod (with the load) to the edge of the table. If the springs stretch further down and the metal rod goes below the table, I will add the distance it stretches below the table to the distance it stretched above the table. I will subtract the second reading from the first to find the whole extension. I will conduct 4 tests and then work out an average.

Obtaining Evidence

Observations:

• As the load was attached to the springs, the springs began to stretch. The springs’ stretching slowed and eventually stopped as the extension got longer.
• The more springs used, the less the extension.

Results:

Test 1

Test 2

Test 3

Test 4

Analysing Results and Drawing Conclusions

        The first observation was made because the load was unable to stretch the springs any further. The second observation, the more springs used, the less the extension, was made because there were more springs supporting the load. Therefore, each spring does not need to stretch as much.

Test 1

        I have graphed all my results in order to determine if my hypothesis that there is direct proportionality is correct. I have also included a graph showing all my results in order to draw a line of best fit to represent all of the tests.

        It is fairly clear that the extensions of the springs are not proportional to the number of springs in a linear fashion, but the extension does decrease when more springs are added. It looks more like a curve with an inverse relationship. The change in extension decreased as more springs were put on. The line of best definitely shows this more clearly. The line is not a straight line.

Test 2

        The second test was very similar to the first. There were only a few minute differences, which were not significant because the graph gave still the same curve. The second graph also showed an inverse relationship

Tests 3 & 4

        These two tests were again practically identical to the others. This is because each test was fair and properly done.

Combination Graph

        This graph shows all of the curves from tests 1, 2, 3 and 4. As you can see, it is clear that the relationship between the extension of the springs and the number of springs carrying a fixed load is inversely proportional; the change in extension (of the springs) diminished as more springs were put added. The fixed load made 2 springs stretched about 28cm. If only 1 spring was used, I can predict that it will stretch    cm. Since the springs that were used could not stretch 70cm without getting ‘overstretched’ or deformed, I can say that springs do have an elastic limit.

Conclusion:

        In conclusion, a load does make springs stretch but not in a linear fashion. The graph is in fact curved meaning that Hooke’s Law cannot really be used in the planning. However, Hooke’s Law gave me some indication of what to expect. The more springs, the less the extension was from the previous number of springs. If the springs were stretched by a load which was too great, the springs would be deformed and unable to return to its original shape. This is because every spring has an elastic limit.

Evaluation

Method:

        The method that I had chosen to use was appropriate. The useful findings reflected the suitability of the method. I think that my method was a good enough to produce the results that I wanted to get. The preliminary work that I had done before my actual investigation helped me greatly. They showed me many important things that I would have never knew if I did the experiments straight away Some minor changes could have been made to the way I conducted my experiment to slightly improve my results:

• Use more springs and test what will happen if 1 springs was used
• Make the load lighter so 1 spring could be used

The improvements mentioned above would have made the investigation more successful and but I believe I have done enough to achieve my aim. It was an overall successful method that contributed greatly to the whole success of the investigation.

Results:

        

        The results that were obtained were very reliable and accurate. They can be easily used to prove that my predictions and hypotheses were wrong. The anomalities were very small and insignificant. The reasons why my results weren’t perfect were because:

 

• I may have mixed up the springs after every test. This would not affect the tests greatly because the springs are practically identical. Some may just have been used more than others.
• At least one variable wasn’t completely controlled.
• The sizes (and also weights) of the play-doh used for securing the springs and load may have varied. This would affect the extension of the springs but not by much.
          

        My predictions were correct that the greater number of springs used to carry a fixed load, the less the extension and if there are fewer springs carrying the load, the extension, or stretching distance will by larger. My hypothesis which was based on Hooke’s Law was not completely correct but the springs did stretch further when less springs were used to carry the load. My results were good enough to support a firm conclusion.

I can suggest further work that would extend my investigation:

• Investigate Hooke’s Law
• Test the extension of springs carrying different objects
• Test the extension of springs made of different material