# This elastic energy - Sample Essay

1. Weigh Lego bungee model. 2. Decide a range of masses to test of which the mass of the figure is somewhere in the middle. 3. Weigh out plasticine into the range of masses making all into a ball. 4. Set up apparatus as shown above. 5. Using the first mass let it hang on the chord. Measure from the top of the plasticine ball, at eye level, the new length of the chord. 6. Repeat the last step twice more to get repeat readings in order to get more accurate readings and to avoid anomalies. 7. Record the results in a table.

Repeat from step 5 with the rest of the masses. Range of masses of plasticine I decided to use masses from 0. 5g up to 8g at o. 5g integrals. Accuracy With a marker pen I marked a 1cm length at the bottom of the chord; this was so that I used the same amount of chord each time for the attachment of the masses. I took two repeat readings and found the average of these to give one, more accurate reading, this will get rid of any anomalies and proves accuracy if all the readings are the same for a certain mass.

Sensitivity

Using 0. 5g intervals will make my experiment more sensitive than using just 1g intervals, there will be more points on the graph making any curves smoother and meaning any readings taken from them will be more accurate. I am also a ruler accurate to 0. 001m and scales accurate to 0. 01g to give more precise readings. Safety I was very careful when carry out my experiment, I was sure to securely attach the clamp to the table using the G-clamp so there was no chance of it falling off and doing anyone any damage.

I also kept my workspace tidy at all times to avoid anyone slipping on anything which may have fallen on the ground. The elastic was very thin and broke quite easily, this could fly up and hit someone in the eye so I was sure to wear goggles at all times. I then calculated the area under the part of the graph for each mass to get the elastic energy for each unit of force.

This elastic energy can then be plotted against extension on the same axis as the graph of g=mg(l+x) and hence the extension at which the jumper will come to rest can be found. Originally the data only went up to 8.000g as I felt this would be an appropriate range of readings with the mass of the Lego figure being in the middle of this range. It turns out that this was not a large enough range as the weights were not being dropped but just allowed to hang in the preliminary experiment. I decided to increase my range to 13. 500 to allow for the extra extension of the elastic when the Lego figure is dropped. If this graph was linear I would be able to use a calculus to calculate the area under the graph, however it is not linear and so I must split the graph up into a series of triangles and rectangles and then find the area of these.