# Marking speed of_sound

8 Mar 2022
1 sur 3

### Marking speed of_sound

• 1. I. ABSTRACT A. The abstract’s aim is to summarise what has been done in the experiment. Briefly describe the experiment done, what physics is at play and give the main results (speed of sound measurement) as well as the main sources of error. B. Give your measurement for the speed of sound and the main sources of error here. The abstract should inform the reader of the main results of the experiment. II. THEORY: A. Format equations better. B. Introduce some physics (resonance) before jumping into the equations. C. Be more precise when you talk about the slope, you need to explain what plot this is associated with. III. SKETCH AND PHOTOS: A. You should have a proper scientific sketch that shows the experimental set up. B. The sketch should show the acoustic resonator and the position of the frequency detector (phone). C. Make the sketch less artistic and more scientific. D. Draw straight lines with a ruler. The sketch should be cleaner. IV. EXPERIMENTAL METHOD: A. Write this in prose, not with bullet points. B. Do not write this section as a recipe but describe what you did. C. Give more details on how you blew, i.e. how you knew you were at resonance. If this was difficult, explain what helped to achieve this. Also detail how you placed the detector to pick up the resonant frequency the best possible. D. Indicate that you measured A and L. V. EXPERIMENTAL DATA: A. Be consistent with significant figures between V in cm^3, m^3 and then 1/sqrt(V). There should be three for values of these three columns. B. Put errors in the headers for the frequency and cavity volume measurements. C. Give all data here, so for the radius and neck length measurements as well.
• 2. VI. DATAANALYSIS: A. Plot: Do it on a computer, it looks much better and is easier to include in a pdf. B. Plot: Draw this as a scatter plot. Here individual points are joined together by segments, which is not a fitting through all points. These have no physical meaning and should not appear. C. Plot: Perform a fitting over all points. This is best done on excel (add trendline and display the equation). This is the best way to estimate the gradient. D. Plot: If you fit by hand make sure to try to draw a line that goes through the point the best possible (as many points above line as below). Do not take individual points from your data to estimate the slope/gradient (unless they lie on the line drawn)!! Instead take two points that lie on the line that you have drawn. Show the points taken on the plot. E. Plot: Plot over a smaller range to eliminate white space. F. Plot: The title should have inform the reader of what is displayed. So it should be something like: “Plot of the resonant frequency of the acoustic resonator against 1/sqrt(V).” G. Plot: The x-axis label should be formatted with the square root symbol. The y-axis should have units. H. Show the equation used that relates the speed of sound to the gradient. I. Give the units for the speed of sound m.s^(-1) and give a consistent number of significant figures with the measurements, 3 here. VII. ERROR ANALYSIS: A. You should give the error on the length and volume measurements. B. Give the percentage difference with the literature value. C. The best way to estimate the error on the resonant frequency is tot take several measurements of f at the same cavity volume (at least three). From these, take the standard deviation and use this as an estimate for the error. VIII. ASSUMPTIONS AND BREAKDOWN A. The resonator is not a perfect Helmholtz resonator. IX. FINAL RESULTS AND CONCLUSIONS: A. This should be written in prose, not as bullet points. B. The conclusion is very similar to the abstract. It should outline what was done in the experiment, give the main results and sources of error. This is a stand alone section.
• 3. X. GENERAL: A. Do not write ‘I’ or ‘we’. Use passive constructions instead. For example, instead of “I measured the length” write “The length was measured”.