Lab 6: Propagated uncertainty in measurements by Jarrod Griffin

Lab 6: Propagated Uncertainty in Measurements

Lab Members:

Jarrod Griffin

Christina Vides

Enio Rodriquez

In this lab, we find the density of metals, and the propagated uncertainty of our measurements.

Introduction:

As the equipment that we use in not 100% accurate, there is always some uncertainty in our measurements. This uncertainty can be amplified when used in equations. This experiment allows us to take measurements, and compare them to actual known values to see how much off we were. We can also compare our propagated uncertainty to how far we were away from the correct value, and check that the actual value lies somewhere within our propagated uncertainty.

Apparatus:

Our equipment for this lab included a caliper, and various cylinders of different metals. We first gathered the measurements for our 2 cylinders, Aluminium and Tin. Our measurements included Mass, Diameter, and Height. We then calculated the volume using the equation for the volume of a cylinder. Once that was completed, we then calculated propagated uncertainty for both Aluminium and Tin, using the square root method of calculation.

Data:

Explanation of Data:

Our experimental value of density of Aluminum was 2.84+-.23 g/cm^3, and 11.31+-2.98 g/cm^3 for Tin.

Actual values of density for Aluminum is 2.7 g/cm^3 and 7.31 g/cm^3 for Tin. Our values for Aluminum were close, and within our uncertainty limits, but for Tin, the measurements were on the very outer limits of our uncertainty.

Conclusions:

This lab was very helpful in learning how propagated uncertainty is calculated and how it can be used to check our values to see if they are remotely correct. In order to get our range of propagated uncertainty smaller, we must use more accurate equipment. While our values of density for Aluminum were very close to being correct, our values for Tin were very wrong. I believe that some measurement was either misinterpreted, or not taken correctly.