Investigate the effects of how springs and elastic bands stretch when weights are hung on them and how springs and elastic bands stretch when the weights are unloaded.

Apparatus:

The equipment that I used for this experiment was:

• Griffin 100g weights x4
• 1 metre ruler x1

• springs x2
• Clamp stand :
• Boss x1
• Clamp x1

Explanation of Hysteresis:

   Hysteresis represents the history dependence on physical systems. If you push on something, it will yield: when you release, does it spring back completely? If it doesn't, it is showing hysteresis. For example, if you place a large force on your fork while cutting a tough piece of meat, it doesn't always return to its original shape: the shape of the fork depends on its history.

Method:

   I set up a clamp stand and then placed a 1m ruler alongside the clamp so I could measure the distance that the spring had gone down and stretched. Obviously the more weight we put on the further the spring went down. I placed the spring on the clamp and measured the starting point of the spring on the ruler and marked it with a removable pen. I did this to make sure I measured from the right place every time and to make it a fair test. Each time I added a weight I measured the distance travelled from the mark I made. I made sure that the spring wasn’t bouncing when I made the measurement otherwise it wouldn’t have been a fair test. We started of with 100g =1N and went up to 500g=5N and then when we got to 500g we took of 100g every time, to find out if the spring had stretched for example when we put the 400g on for the first time it was 16.6m and when we took off the 500g it was 16.4 cm. Every time we did this we recorded the results.

I set up a clamp stand and then placed a 1m ruler alongside the clamp so I could measure the distance the elastic band had gone down and stretched. Obviously the more weight I put on the further the elastic band went down. I placed the elastic band on the clamp and measured the starting point. I marked the starting with a removable pen so I could measure how far the elastic band had gone down every time. Each time I added a weight I measured the distance travelled from the mark I made. I made sure the elastic band was still before I took the measurement otherwise it would not have been a fair test. We then repeated the process of what we did with the spring investigation. (In bold above) 

To make it a fair test I:

• Made sure the spring and weight were still before I took the measurement.

• Made sure the ruler was vertical.
• Did each result 3 times and took an average.
• Marked the starting point of the (elastic band/spring) with a removable pen.

Note: If one result stands out from the rest, I will do the result again or eliminate the result and then take an average.

Diagram of apparatus used for spring investigation:

Results of spring investigation:

Graph of spring investigation (hand drawn and computed graph)

Diagram of apparatus used for elastic band investigation:

Result of elastic band investigation:

Graph of elastic band investigation. (Hand drawn and computed graph)

Evaluation: 

The first graph for investigating springs clearly shows that my prediction was correct; the more weight that was loaded onto the spring the higher the distance was from the original starting point. My theory that the 500g weight would not make the spring go past its elasticity was correct  The graph show the cm stretched steadily increases as the more weight is loaded onto it.

   The second half of the elastic band graph shows basically the same results of the spring graph, but as I predicted the unloading was different to the loading up of the weights. The unloading gave higher results of the cm stretched unloading than when it was loaded up. This is because I believe that hysteresis has occurred.

Conclusion:

   I believe that this experiment was successful in both proving my predictions to be correct and also to show the occurrence of hysteresis. I think that the results show clearly what I had predicted. I believe that these results are correct, because I made three results and averaged them; also there were no anomalous results. These results were also consistent.

   Although this experiment may not have given precise results because the measuring equipment, I believe that if I had better measuring equipment than the results shown may have been more precise. But I still believe that the overall results would prove my prediction correct.

   To extend this experiment I could have done the unloading for the spring as well as the elastic band to see if hysteresis would be shown.