An Investigation into the elastic properties of different thickness of elastic bands

An Investigation into the elastic properties of different thickness of elastic bands.

Planning

Aim: the aim of this experiment is to find out what effect that different thickness’ of elastic bands has to the amount they stretch under a series of different weights. To test this I shall use different thickness’ of elastic band that are all the same length.. The final adjustment I shall make is to measure the thickest band with greater weights as well. This will show the effect of weight and its relation to the amount the band stretches.

Hypothesis:

According to hook’s law the expansion of a spring is proportional to the weight it supports. If the same applies to the rubber band it to should increase in the amount it has expanded when a greater weight is applied. I therefore am able to predict that although not all the time the band will expand at the same rate as the amount of weight applied. However elastic bands are not quite as elastic as springs and so I do not expect this to be completely true. I also expect that the thicker the band the greater the weight will be required to stretch the band at the same rate. This entire put together should mean that as the pull on the bands is increased so the amount they stretch is. This should also mean that the amount they increase by should be smaller the thicker the band is. (E.g. the thinnest band might increase by 3cm for each extra Newton, the second thickest might increase by 2 cm and the thickest might increase by just 1cm. this would be up to a point where the bands would increase quicker. This point would be a greater force for each of the thicker bands with the thickest band needing the greatest pull before this occurred.)

Diagram:

Variables:

The 2 things I am going to change (on purpose) is the thickness of the band and the amount of force pulling on the band. I will only change one variable at a time. The fact that I shall have to do it over two days could affect the temperature of the band and this could have a direct effect on the results of the elastitisity band. I shall however use the same equipment for the experiment. The person who looks at the elastic band shall be the same all the time. ...

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Diagram:

Variables:

Measurements:

I am going to measure the length of the band between 0.1cm and 30 cm. This shall be accurate to 0.1 of a cm. The weight being used on the band shall be measured between 10grms and 500grms.

Plan/Method:

First of all I shall start of with the thinnest band and with the 10grm weight. After I take down the result I shall increase the weight by 10grms and take the result again. I9 shall repeat this until I get up to 150grm where I shall increase the weight by 50 grams and take the result. Once I get up to 500grms I shall stop. Once I have done all the results for that band I shall repeat the experiment again but with the thicker band. Once that thickness of band has been done I shall do the experiment again but with the thickest band.

Apparatus:

I am going to need a 30cm ruler, a clamp stand, 3 different thickness of elastic bands, some tape and some weights. These weights will have to be able to get up to 150grms increasing in 10grms and 500grms increasing in 50grms so the best would be 15 10grm weights and 7 50grm weights.

Risk assessment:

The only problem could be if someone was messing about and he fired a band into someone else’s eye. So to avoid this we shall all not mess about.

Analysing evidence and drawing conclusions

Analysis:

All the band’s start of looking the same with a pattern like Band 3 however bands 2 and 1 go off from this pattern. For band 1 this happens after it reaches 100grms and beyond 10cm in length. This is where it goes up dramatically. For band 2 this occurs around 150 or 10cm again. It is roughly the same in both cases. After this point the bands length rises dramatically.

Conclusion:

When a load gets too much for an object. The object no longer goes back too its original size and it now gets stretched to a different degree to that which it did previously. This is because there are small elastic atoms which hold the band together when a load gets too much these come out of place. So it gets stretched and cant come back together to its original shape as the atoms which hold the band together this means it does not have all the atoms in there right place and is stretched.

This is shown in band 12 and Band 2 where the band suddenly stretches a lot greater then previously. These results compliment my hypothesis very well.

Evaluating Evidence

The Evidence:

I had plenty of evidence as a clear pattern can be seen in each of the band graphs. These patterns also make a lot of sense. The evidence was very accurate however it was not as accurate as it could have been. A few pieces of evidence can be seen to make not as much sense in the whole feel of the graph. However these differences are not massive. The evidence is still good enough to support my theory. As there is enough of it and it is quite accurate.

Improvements:

I could have improved my experiment by using a ruler to check out the length to be sure. This would have made my results more accurate but probably would have made the pattern the same. I could have extended my experiment by including more results between 150 to 500.