Calculations Discussion a = 2(slope)=2(490.45)=980.9 m/s (980.9 - 9.8) % error 9.8 (100%) 9909% This lab did not go like we expected. The first graph was curved, not a line. But squaring the data fixed the graph and we got a line graph for graph #2, like we expected. So the lab sort of worked out like it was supposed to. We got a value of 980.9 which is a bit bigger than the expected value of -9.8. This is probably due to the effects of air friction which we always neglect. As well, we could probably have improved results a lot by using a digital device like a laser rangefinder to measure the distances and maybe got better results. Also, I got a 9909% error, so it is likely that something went wrong with my calculations but I don't know where. Conclusion Some of the values we got in this lab were way off from expectations, but we got a linear graph. So the lab was a success. 2. You measure the time it takes for a pulse of sound emitted by a speaker to travel certain distances, obtaining the following results: (Out of 6 marks) Distance (m) 10.0 0.1 20.0 0.1 30.0 0.1 40.0 0.1 50.0 0.1 60.0 0.1 70.0 0.1 80.0 0.1 Sound Propagation Time (s) 0.032 0.001 0.057 0.001 0.088 0.001 0.121 0.001 0.147 0.001 0.177 0.001 0.201 0.001 0.235 0.001 a) Plot a graph of time (y-axis) vs. distance (x-axis) with uncertainties. Give your graph a title and axis labels following the graphing with uncertainties guidelines of the Introduction and the Excel Graphing Template. (2 marks) - Must submit a screenshot of the graph with your report. b) Determine the best fit line through the data points. Make sure that you also calculate the uncertainty in the slope and the y-intercept following the guidelines of section 4. (2 marks) c) Using the equation of the line from part b, determine a value for the speed of sound, including an uncertainty.(2 marks) Rule: To determine the uncertainty on the slope and y-intercept of a graph of N data points with lines of best fit, maximum and minimum slope drawn and with the associated values of slope (m) and y-intercept (b) determined perform the following calculations: m = mbest fit 2 1|mmax-mmin N 1|bmax-bmin b = bbest fit 2 N PART 2 (out of 5 marks): read the following formal lab reports requirement, and comment on the two lab sample reports that follow. Marking rubric: 1. Comments should be clear: compare reports against the expectation of reports 2. Clearly identify as one report as strong. Clearly indicate the strengths of the report with specific examples. 3. Clearly identify as one report as weak. Clearly indicate the weaknesses of the report with specific examples. 4. Writing is clear, easy to understand and contains at most minor typos. 5. At least half a letter page long. Experiment #7: Falling Objects Objective: To determine the relationship between the distance a object falls and the time taken. To determine the acceleration of a falling object Theory: 1 3 = vt+at 2 1 slope = Apparatus Ball dropping apparatus, photogates, metal ball, computer timer Procedure 1. Set the ball release mechanism at a position 2. Release the ball and record the fall distance and the time taken 3. Repeat step #2 4. Plot a graph of fall distance vs. time. 5. Plot a graph of fall distance vs. time 6. Find acceleration from the graph Data (2) (1) Displacement Time Time squared 5 0.099 0.0098 10 0.143 0.0204 20 0.200 0.040 40 0.280 0.0784 60 0.350 0.123 80 0.406 0.165 100 0.447 0.200 120 0.495 0.245 Graphs 140 Graph #1 Y-Axis Label 120 100 80 60 60 40 20 y 289.83x-33.298 0.1 0.2 0.3 0.4 0.5 0.6