Determination of Coefficient of Friction Essays

Determination of Coefficient of Friction Essays Determination of Coefficient of Friction Essay Determination of Coefficient of Friction Essay First of all, I prepare my working place and start my determination. All my measurements are recorded to the table above. For more accurate results of   kinetic I recorded data with 5 different weights.  The smallest graduation of the spring scale is 0.1 N. According to this, the absolute uncertainty of weight of the block is 0.05 N. I do not add additional uncertainty as I did not encounter any further difficulties in weight measurement. I used weights provided by my teacher. Those weights were precisely 1 N each. In the table I only provide the number of them and therefore I take it without uncertainty.  Once again the smallest graduation of the spring scale is 0.1N and according to this, the absolute uncertainty of friction force measurements should be 0.05N, but I decided to take this uncertainty as 0.1N as it was hard to determine the friction force correctly. I needed to pull the block with the weights at just that force to overcome the friction. I needed to pull equally and using the constant force. It was hard to do, so I decided to add some further uncertainty. Data processing:  When determining the kinetic friction coefficient the mg is equal to the normal force. In each situation I add the weight of the block with weight of the number of weights added. As my used weights were very precise and provided by my teacher I do not include uncertainty to their weights. They were 1N each. Therefore, I leave the absolute uncertainty of the normal force the same as the weight of the block as the same uncertainty remains. ?Normal force = ?weight of the block + ?weights - ?normal force = ?weight of the block + 0. For each situation with different number of weights, the normal force differs as well. I calculated the normal force in this way:  Normal force = weight of the block + n x weight of one weight - Normal force = 0.60 + 1n, where n is the number of weights added.  First of all I measured the length of the wooden plane. I used a meter rule which had a smallest graduation of 0.1 cm. Therefore, I should take the absolute uncertainty of length measurement as 0.05cm, but I decided to take it as 0.1cm due to the fact that wooden plane could not have been in a perfect rectangular shape and therefore length at different positions could be different. I decided to investigate and to check the static coefficient of friction in different situations, so I include the number of weights attached to the wooden block. I provide them as integer numbers.  Further I collected raw data of the height just before which the wooden block started to move. I collected these readings with a meter rule which smallest graduation was 0.1cm and therefore the absolute uncertainty of height measurements should be 0.05cm but I decided to take the absolute uncertainty as 0.3cm due to the fact that wooden plane was lifted by a human and therefore it was hard to identify the correct height.However the biggest deviation from the mean is 0.06, so this number will be taken as the absolute uncertainty. Now I can compare my result with literatures. In Giancoli Physics page 97 it is provided that the coefficient of static friction of wood on wood is equal to 0.4. The percentage discrepancy is equal to 45%. Also, the percentage uncertainty is equal to 27%. I will discuss these finding in conclusion and evaluation part.  Conclusion and evaluation:  The first part of my determination, where I had to find the kinetic coefficient was done more precisely, but not more accurately. The percentage discrepancy compared with the literatures was 0% what is a great achievement, but however the percentage uncertainty was 100%. In the second part discrepancy was 45% and percentage uncertainty was 27%. The percentage uncertainty of the static friction coefficient is quite good, but still the result and determined coefficient is quite far from given literatures value. Therefore, I have to state the weaknesses and limitations of my determination. Some errors were encountered and the percentage uncertainties are quite big despite the fact that I tried to be as accurate as possible. Next time I may try to improve my determination with suggestions provided further and then more accurate results could come. First of all, the main weakness of the determination was human factor as it was needed either to pull uniformly or to lift the plane very slowly and uniformly as well. It was clearly the weakest part of all determination as uniformity was very difficult to achieve. Of course, calculating means helped me to determine the coefficients more precisely, but huge uncertainties were still left. Moreover I could blame the instruments as I had to use quite many of them, but the uncertainty they provided was relatively small. Furthermore, some systematic errors have occurred as I had to do a lot of calculations and roundings during the data processing part. Also, the instruments may have been badly calibrated and this could have affected my determination. However, systematic errors are not so important because even if they even were encountered, they were very small. Another thing is with random errors as they were really significant because the percentage uncertainty shows quite high result. I could provide several suggestions to improve the determination. First of all, I would rather use bigger and longer plane and bigger block. Then, as I would still use the same equipment with same absolute uncertainties, the percentage uncertainty would be reduced significantly. The uncertainty would be less important and more accurate results would come. Also, human factor uncertainty would be reduced because it would be easier to pull uniformly or to lift the plane. However, my suggestions would only lesser the uncertainties, but they would not totally cancel them.