Safety In this experiments the staple that is fired has sharp ends to it and so it can be dangerous. So throughout this experiment I will wear goggles and work in an area away from others. Method 1) Set up the equipment as shown in the diagram on the first page. 2) Cut a 8cm of string 3) Attach the string to the weight holder (weight holder weighs 100g) 4) Attach the other end of the string to the elastic band. 5) Measure the extension of the elastic band and record it. 6) Get into the right position to record the height of the staple.
7) Cut the string and record the height to the nearest 5cm. 8) Repeat each test 3 times and then take an average of the height. 9) Repeat the same experiment using the next weight (200g). Obersavation and Recording To calculate the amount of elastic energy stored in the elastic band at different extension, I drew a graph based on the results shown below. The area under the graph is represented of the elastic energy stored at various extensions.
From my graph, each 1cm 1cm square is represented ofThe elastic energy is an approximation. I have tried to be as accurate as possible whilst counting the squares. I found that the distance from the floor to the ceiling was 3. 32m and the distance the elastic band traveled from rest while attached to the clamp to the point where it hits the ceiling to be 2. 07m.
From looking at the results we can see that the maximum height reached by the staple, the point where it hit the ceiling was when its extension was 10cm. From this I can calculate the amount of elastic energy stored in the band using my graph. I can also calculate the amount of energy transferred to the staple, ie the potential energy gained, by using the equation mgh.
Evaluation In the experiment I was trying to measure the efficiency of the energy transfer for the staple fired into the air, by the elastic band. The energy conversion in the experiment is the transfer of elastic energy stored in the elastic band to potential energy gained by the staple after it has fired into the air.
Elastic energy i?? Potential energy From looking at my results the general pattern is that an increase in extension increases the height of the staple that is fired. The graph I have produced, force extension graph also show this. The graph does not follow Hooke’s law, as the line is not straight. The values I collected for the elastic energy was 0. 170 J and energy converted into potential energy in the staple after it had been fired was 0. 041 J. The percentage efficiency for this energy transfer was 24. 1%.
This means only a small amount of elastic energy was converted to potential energy and most of the energy had been lost. The reason for this could be due to the air resistance. I stretched the elastic at different lengths and observed how far the staple shot off as a result. At first the relationship between the extension and the distance was close, nearly the same. Then air friction could of decreased the distance traveled for a given stretch. This would mean that the staple would have gained less potential energy.
Also this experiment involves the transformation of elastic energy to potential energy between the elastic and the staple. But when the elastic band is stretched and released this involve the transformation of elastic energy to kinetic energy so some energy could have been lost due to this kinetic energy. Another reason could be that when stretched, energy could of been lost as a form of heat. When the elastic band is stretched the rubber polymer chains become more orderly and H bonds form between these chains. This H bond formation is exothermic therefore the stretched elastic band will feel warm and heat will be lost.
(Reversing this process (when unstretched), the polymer chains become disorderly, the H bonds break and as this is endothermic, heat is absorbed and the band feels cool. ) This heat energy lost will have an effect on the transfer of energy between the elastic band and the staple. To keep this experiment as accurate as possible I took 3 reading for each test and then I took an average. I used appropriate and reliable equipment and used them properly. When taking the results I will also draw the graph at the same time so if any chance an anomalous result does occurs I can go back and repeat the same test to get the right result.
I also design the experiment so I would be as accurate as possible using the equipment from the lab. I thought that the experiment went well, the results that I got I thought was accurate and reliable. I thought that the experiment was well planned, reducing any factor that would lead to unreliable results. Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.