8-Sep.-14: Propagated Uncertainty

PURPOSE: To learn more about error analysis and propagated uncertainty.

This activity was done in two parts. For the first part we measure the density of three different metals - for the second part, we determined an unknown mass.

Beginning the the equation of density, 

we suddenly realized what information was required to measure the density of our three metal cylinders. 

To measure the mass we used a provided mass scale which was accurate to 0.1 g.

To measure the diameter of each cylinder, we used calipers and divide the value to attain the radius.

The cylinders had a short enough height which allowed us to also use the calipers for that measurement.

The Data we collected:

Starting with the Volume of a cylinder,

we derived an expression to measure the uncertainty in the density of the cylinder given that we measure the mass, the diameter and the height of each said cylinder.

The value of density that we calculated for our Brass cylinder was 8,432 kg/m^3 ± 134kg/m^3.

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For the Second part of the activity, we found the mass of an object using the concepts of tension and Newtons laws.

Our apparatus included two poles secured to a counter top with two strings supporting the unknown mass. Attached to one of the supporting strings was a spring scale to measure the tension in the string it is attached to.

Examining the apparatus of mass #6, we note that there is only one spring scale on the right string.

From the one scale we determined a value from the unknown mass.

A great day for physics.