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GVSU EGR 220 - Formal Report Template

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Process Variability: Shooting at a TargetExecutive SummaryIntroductionApparatusExperimental ProcedureResults and DiscussionConclusionAppendix AAppendix BProcess Variability: Shooting at a TargetExecutive SummaryThe purpose of this experiment was to measure the accuracy and precision of a launcher which fired aprojectile at a target, and to take measurements and compare them. To achieve this, projectiles were shotten times at a target using an air launcher set at 50 psi. The x-distance, y-distance, and straight-linedistance of the impact points from the bullseye were measured using a meter stick in centimeters. Theflight of the projectiles was analyzed using a run chart. The variability in measurement methods was alsoanalyzed by calculating the percent difference.From the analysis of the impact points of the projectiles, the variability in the flight of the projectilesresulted in a mean distance of ___cm for the ten shots of projectile #1 from mold E. Sources of processvariability were the uncertainty of the meter stick measurements being +/- 0.05 cm, the paper possiblymoving slightly from the impact of each strike by the projectile, large marks made by the projectilecausing uncertainty of where the center of the projectile impacted the target, and also slight movement ofthe launcher tube while loading the projectile in for each launch. From this experiment, it was determinedthat the shooting the projectiles resulted in low accuracy and low precision.EGR 220 Engineering Measurement and Data Analysis Lab Section Date Performed: September 6, 2018Date Submitted: September 13, 2018Instructor:IntroductionThe objectives of this laboratory activity were to study the variability that went on during the measuring and calculating processes by comparing the final measured results to the calculated results, and to apply the concepts of precision and accuracy to study data and properly use the tools in the lab such as calipers and meter sticks. In order to assess process variability, Alumilite projectiles shot from an air launcher at a target. The x-distance, y-distance, and straight-line distance of the impact points from the bullseye were measured using a meter stick. When taking measurements, accuracy and precision are important. Accuracy is the correctness of a measurement while precision is the exactness of a measurement. When shooting at a target, the accuracy of the shot is how close the impact point is to the bullseye and the precision is how close each impact point is to each other.To evaluate the distance of the impact point from the bullseye, it is possible to measure the straight-line distance directly or the x-distance and y-distance of the impact points can be measured and the straight-line distance can be calculated using the Pythagorean Theorem, shown in Equation 1.a2+b2=c2 (1)Where a and b are the lengths of the orthogonal sides of a right triangle and c is the hypotenuse.To compare these two experimental quantities, one being the direct measurement and the other being the calculated value based on two experimentally measured values, the percent difference can be used, shownin Equation 2. Neither value can be considered a correct value but the percent difference allows the variability in the experimental values to be compared.% Difference=|Quantity 1−Quantity 2|12(Quantity 1+Quantity 2¿)× 100 %(2)Where Quantity 1 is one of the experimental values being compared and Quantity 2 is the other experimental values being compared.ApparatusCaliper – identification # 3, precision: 0.02 cmAlumilite projectile #1 from mold EProjectile launcher – identification # 2, air valve precision 50.0 psiMeter stick – precision .1 cmExperimental ProcedureThe inner and outer diameters of the launcher were taken and recorded, and the projectile was loaded into the tip of the launcher. Paint was added to the tip of the projectile to leave a mark where the projectile hit the target for measurement purposes. The Projectile was then pushed to the back of the launcher with a pole. Once it was certain that the pathway of the projectile was clear, the projectile was launched out of the pipe with a pressure of 50.0 psi. The projectile was launched for a total of 10 trials, leaving 10 points 2on the target. Once the 10 marks were left by the projectile on the target, the distances from the x-axis andy-axis were measured and recorded, and the total distance from the bullseye to each point was also measured and recorded. Results and DiscussionFor a majority of the results, the percent difference that was calculated was very low. This can be seen in Table A-1, where all percent difference calculations are below 1.50 except Trial 1. Throughout the 10 trials, the projectile landed in many different places around the target, as seen in Graph A-1. This run chart indicates that the launching of this projectile is not consistent from trial to trial, which could be the result of many things. A few sources of variability could be the shape of the projectile being morphed, theuncertainty of the meter stick being +/- 0.05 cm, and the launcher being moved slightly each time the projectile was loaded. The average percent difference was calculated to be 1.227%. The largest percent difference was 7.41%, while the smallest percent difference was 0.00%. The smallest percent differences were from the trials in which the projectile landed the furthest away from the bullseye, and the largest percent difference came from the trial where the projectile was very close to the bullseye. This is because the denominator in the percent difference is both the X and Y distances divided by two, and when the distances are much larger, the value is divided by a larger number, making the percent difference smaller. When a larger distance is measured, since the uncertainty of the meter stick is 0.05 cm, this uncertainty becomes less important than compared to when measuring a smaller distance, thus making percent difference larger for smaller distances. The data points from the 10 trials were neither accurate or precise, looking at Graph A-2. There is no specific grouping of data points, making in unprecise, and hardly any of the points are near the origin, making the data inaccurate. One source of error in this lab was the shape of the projectile being morphed, causing an unpredictable amount of pressure escaping around the sides of the projectile due to an inconsistent diameter. Another source of error in the lab was the error in


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