The aim of the experiment is to find the relationship between the distance and the sound, produced between an elastic band and a wall. The will be done by pulling back an elastic band at a different distance each time and shooting it at the wall and then recording the sound it produced using a speed level meter. Pulling back an elastic band with an increasing distance each time and then shooting it at the wall will result in increasing speed in which the elastic band would go.This would mean that the kinetic energy would increase too because the theory of the kinetic energy states that the kinetic energy is proportional to the speed squared. But as the elastic band hits the wall all the kinetic energy gets lost either in the form of heat or sound. So, the more kinetic energy there is the more sound would occur. Thus, it can be predicted that as distance increases the kinetic energy increases.
In this lab the manipulated variable would be the distance of the elastic band that is pulled. The speed and time would also be the manipulated variables. The responding variable would be the sound intensity produced by the elastic band. The controlling variables would be the position of the apparatus, distance of the wall from the elastic band, same apparatus used and finally the type and surface of the wall.To control the variables, the positions of the apparatus should stay the same such as the speed level meter, the elastic band and the wall etc.
the distance of the elastic band should be kept 12 cm away from the wall and same apparatus should be used. This could be done by using the materials from the same brand. The wall should be solid surface of the wall should have no holes so that there would be no difficulties for the sound level meter to get sound intensity. The materials that would be required for the experiment is 1-elastic band, 1-wall, 1- Speed level meter, 1- thumb tack, 1- block of wood, 1 – table clamp. 1 – rulerConclusion:In this investigation, a sound level meter was used to determine the sound intensity for an elastic rubber band which hit the wall (whose position was at a distance of 12 cm away from the elastic band). The average of the sound intensity was calculated and thus the graph of Distance vs. sound intensity was made.
Through the process listed at the beginning and the analysis throughout, it is found out that the sound increases by proportionality factor of about 2.5 + 0.1 units of sound/cm as the distance increases. This result is found from the slope of a liner graph which in this case tells the proportionality factor between sound and distance.
Evaluation:The lab was a success. This can be seen form the linear relationship between distance and sound that was got from the data. But the slope varies about 0.1 units of sound/cm which is very small which means that there were some minor problems done during the experiment which caused the relative error to increase. One problem was the angle at which the elastic band was shot at the wall.
The angle was not always parallel to the block of wood. This brought change in the direction of the elastic band hitting the wall which also resulted in the distance of the elastic band from the position of the sound level meter.Thus, the sound intensity recorded by sound level meter would not be accurate. Another problem was the external sound. The sound level was kept on high mode in the sound level meter which means that it was able to catch sound up to 150dB. The external sound for example, the noise of the people talking or the objects falling nearby can be captured by the sound level meter pretty well which can bring change in the data. Thus, the sound intensity recorded by the sound level meter in this case would not be right.
Improvements:There were not any other errors caused by the apparatus. It was stable enough for the experiment. Therefore, there is no need to change the apparatus if this experiment would be done again.
However, a protractor could be used to measure the angle so that there could be no problem with the angles in which the elastic band is shot at. Another improvement would be to do this experiment in a quiet place such as a quiet room, so that there would not be any other sound captured by the sound level meter than the elastic band’s when hitting the wall.