Investigation to show how Elastic Bands Behave Under Load
The aim of the investigation is to determine how elastic bands behave under load. Before I begin the investigation I will carry out a preliminary experiment into the behaviour of a spring, which I believe will not act in the same way as the elastic band.
In the preliminary investigation a spring was put under load and the results were as follows:
From previous knowledge of Hooke's Law, which explains, extension is proportional to load until elastic limit is reached. The preliminary experiment with the spring shows, that they obey Hooke's Law up until the point of permanent deformation (elastic limit).
I think that the thinner rubber band will have a bigger extension than the thicker band and the longer band will have bigger extension than the shorter band.
I think the longer rubber band will have the biggest extension because the molecules within the rubber band are larger and are less intertwined and the molecules are therefore stretched further causing it to have a greater extension. Although the band is stretched the rubber band does not obey Hooke's Law. The elastic band will regain its initial shape and it behaves elastically. The thinner band will also have a longer extension because the molecules are less intertwined and so the band isn’t as strong, when weight is applied the band will stretch further than a thicker rubber. In the thicker rubber band the molecules are more intertwined therefore the band will become stronger so the band will not stretch as far. In the shorter rubber band the molecules are much smaller and are more intertwined, this causes the band not to stretch, as far so it will have a smaller extension. This graph below shows how the rubber behaves.