experimenters: Georgie, Josephine and Dolphy
Abstract
This lab looks at the difference in precision and accuracy when using a Vernier caliper and a ruler. Both instruments were used to measure the diameter and the length of four different metal rods, as well as an electronic scale was used to measure the mass of each rod. Then with all the measurements collected, calculations were done to find the volume, density, percent difference and percent error.
IntroductionIn this lab we were exploring different ways of measuring objects and how the tools we use effect the precision and accuracy of the final product. Throughout the lab we discovered four main fundamentals of measuring and they are the following;
We practiced and exercised these fundamentals throughout the lab as we measured the diameter and length of four different metal rods with both a Vernier caliper and a ruler, we also measured the mass using an electronic scale. We then used those measurements to calculate the volume and density of each rod. Next we collected the results of another group also doing the lab and the actual values and compared the two different values to our data, this abled us to calculate the percentage of error as well as the percentage of difference. HypothesisWhen using a Vernier caliper as opposed to a standard ruler, the measurement will be much more precise which will then conclude in a smaller error and difference percentage, producing a more accurate result.
Materials Used in this labprocedureFirst place your first metal rod on the plate of the electronic scale and record the result. Do this for the other three rods, recording the result after each rod has been placed on the scale. Now measure the length and the diameter of each rod in centimeters (try to be precise as possible) using the ruler, record the result for every rod. Now measure the same parts of the rod (length and the diameter) in centimeters, however this time use a Vernier caliper and record the results. Now calculate the volume (V) for each rod both using the vernier caliper and the ruler, using the equation listed below (r is equal to the radius and l is equal to the length.), record results. Calculate the density (p) of the each rod using the equation listed below (m is equal to mass and V is equal to the volume) for both the measurements taken of each rod, with the ruler and the Vernier Caliper, and record result. Now collect another groups values for the density of each rod for both vernier caliper and the ruler, and calculate the percent difference of each rod using the equation listed below (E1 is equal to the first experimental value and E2 is equal to the second experimental value). Finally, compare your results to the known values for each rod, then calculate the percent error using the equation listed below (T is equal to the true value and E is equal to the experimental value). Clean up materials and analyze results.
Formulas |
Data
Width of Rods
Length of rods
Mass of Rods
It is interesting how four metal rods when held in a hand felt that they weighed the same amount, however when measured with an actual tool there was a large difference in mass.
Volume and Density of rods
PERCENT DIFFERENCE of Density
The majority of the rods when measured with a ruler resulted with a larger percent difference than those measured with a vernier caliper.
Percent Error of Density
There isn't a clearly more precise tool, as each resulted with two rods that had a larger percent error and a smaller percent error, compared with the other tool used.
Analysis
Based on the data that was recorded from this experiment, the percent error using a vernier caliper was smaller compared to the percent error of the ruler for two of the rods and the other two had a percent error that was larger. The hypothesis that was stated at the beginning of this experiment was partially correct as two of the four values measured with the vernier caliper were more accurate compared to the measurements of the ruler.
Discussion
After the all the measurements for this lab were collected, recorded and calculated, the final analysis was that the measurements of the rods using a vernier caliper and a ruler were sometimes more accurate than the caliper and sometimes not. The density measurement was used to calculate the final percent error compared to the known value, the results stated that the percent error of the vernier caliper were partially smaller and partially bigger when comparing to the percent error of the ruler. Meaning that two of the rods had a percent error that was bigger than that of the ruler percent error and smaller than that of the ruler percent error. However the caliper can still be seen as more accurate in this experiment because the percent errors of the caliper were much closer in margin then those of the ruler. Though the error of percent in some cases was larger for the caliper, the value was still very close to the true value.
This analysis was unexpected as the hypotheses of this experiment stated, that all rods measured by the vernier caliper would be more accurate to the known value. The vernier caliper, when compared to the ruler, is much more precise when measuring objects. It is made so that the human eye is able to estimate measurements to further decimal points with ease, making it more precise. However in this experiment the ruler in some cases was more accurate to the known value of density. Potential experimental error may have been in the measuring and recording process, resulting in the data given to be unexpected. Perhaps measurements were not recorded correctly and therefore calculated incorrect results. Also maybe each measurement should have been measured more than once to be certain that it is reasonable or with a number of trials done the average of the measurement could have been calculated.
To further the research on this topic perhaps another experiment could be conducted, adding in another tool to compare with the vernier caliper and ruler. This would then emphasis the precision and accuracy of the tools as they would be compared to different tools. Also another object to measure could be selected, maybe an object with different dimensions and therefore more measurements to calculate and therefore enabling the experimenter to be able to compare the precision and accuracy of each tool used.
Different measuring tools are created to provide the most accurate and precise measurements when measuring different objects. Each tool has strengths and weaknesses when it comes to which object is better to measure it with. For example a vernier caliper is a great tool to use when measuring a pipe or a width of a pencil, a measuring tape is best for measuring the circumference of a head or a water bottle and a ruler is a good tool to use when measuring the length of a picture or the length of a book. Each tool listed is used for the same purpose however works in different and unique ways.