Density Lab

Objective: To determine the density of regularly shaped objects.

Purpose: To introduce concepts in numerical analysis and error analysis in measurement.

Equipment: Assorted objects, balance, Vernier caliper.

You will be working in groups of two for this lab.

When you are complete, please add your data to this spreadsheet.  (Note you will need to make a duplicate copy from the master sheet, label it with your initials, and add your data to that form.)
How to input the data:

1. Right click on the tab labelled "Copy Me"
2. Rename the tab with the names of your group
3. Input your measurements for parts I and II

Procedure:

Part I  (For this part of the lab you will need one copper cylinder and one glass sphere) 

1. Using the vernier calipers, determine the radius and height of the copper cylinder to the nearest 0.01cm   
2. Each measurement should be done SIX times alternating between you and your partner taking the readings. 

3. Repeat the procedure for the radius of the glass marble.



Part II (For this part of the lab you will need five objects of the same composition)

1.  Using the vernier calipers, determine the volume of each object

2.  Determine the mass of each object using the triple beam balance.

3.  Repeat steps one and two using another set of five objects. 

Calculations/Analysis

Part I

• Calculate the volume of the cylinder and the sphere for each set of measurements, and then find the mean and error of your volume calculations.

• Which object had the greatest variation in volume?  Is this result of human or equipment error?

Part II

• Use your calculator to determine the volume and density of each object. Determine the mean and error for each set of objects with like compositions. Compare your results with the accepted values below:

(All values in grams per cubic centimeters)

Aluminum: 2.70

Brass: 8.44

Copper: 8.93

Steel: 7.82

• Make a graph of the mass vs. volume for the like objects.  
• Can you determine the density from this graph? Explain. 
• Since all of your objects are made of the same materials, how would you expect your graph to look? 
•  Draw a dotted line on your graph to indicate the expected answer.

• Identify two sources of error that may have affected your results. Explain how they affected your results and what changes you could make to lab to correct them next time.

Questions:

Part I
1. When measuring the length and diameter of a cylinder, which dimension should be measured more carefully? Explain.

2. Why are several measurements taken for parts 1 & 2?

3. Cylinder A is made of metal twice as dense as Cylinder B. Both cylinders have the same mass and height. What is the ratio of the radius of cylinder A to the radius of cylinder B.

Part II

• Did the size of the object affect the accuracy of your results?  Explain.

• Define the following terms
• Accuracy
• Precision
• Resolution
• Sensitivity