Name_____________________________________ Date_______________ Block___
SAMPLE LAB REPORT
Digital Scale or Triple Beam Balance: Which Gives More Accurate and Precise Data?
Introduction/Purpose
Before 1982, pennies were made of mostly copper. However, the copper in a penny was worth
more than the actual penny was worth, so people could sell the copper in pennies and make a
profit. This kind of action would cause the U.S. mints to lose money. After 1982, mints are made
if mostly zinc – only a small percentage of a penny is copper. Zinc has a lower density than
copper, so the pennies made after 1982 should also have a lower density. The purpose of today’s
lab is to see of the pennies made after 1982 have less mass than the ones made before 1982. We
will also be using two different kinds of scales (digital scale and triple beam balance) to measure
the pennies because we want to see which gives more accurate and precise data.
Hypothesis
I predict that the pennies from after 1982 will have a lower mass than the pennies from before
1982. Density is mass over volume, and since the size of the pennies didn’t change, their lower
density after 1982 must mean they have a lower mass. I also predict that the digital scale will
give more accurate and more precise data, as long as it is calibrated correctly. There is much less
human error with the digital scale, which would make the data gotten more accurate. The digital
scale can also read out more decimals, so that would make the data more precise.
Materials
 10 pennies from before 1982
 10 pennies from after 1982


Triple beam balance
Digital scale
Procedure:
1. Zero the triple beam balance.
2. Find the mass of each penny in grams and record the date of issue and its mass in
the data table. Do this for 10 pennies from before 1982 and for 10 pennies from
after 1982.
3. Repeat steps 1-3 with a digital scale.
Data
Name_____________________________________ Date_______________ Block___
Error Calculations
 Before 1982 pennies with triple beam balance
max  min 3.3  3

 0.075 g
o Standard deviation: stdev 
4
4
experiment al result  accepted value
3.19  3.1
o Percent error 
 100 
 100  2.9%
accepted value
3.1

After 1982 pennies with triple beam balance
max  min 2.6  2.5

 0.025 g
o Standard deviation: stdev 
4
4
experiment al result  accepted value
2.58  2.5
100 
100  3.2%
o Percent error 
accepted value
2.5

Before 1982 pennies with digital scale
max  min 3.12  3.01

 0.0274 g
o Standard deviation: stdev 
4
4
experiment al result  accepted value
3.072  3.1
 100 
 100  0.9%
o Percent error 
accepted value
3.1

After 1982 pennies with digital scale
max  min 2.55  2.45

 0.025 g
o Standard deviation: stdev 
4
4
Name_____________________________________ Date_______________ Block___
o
Percent error 
experiment al result  accepted value
2.48  2.5
 100 
 100  0.8%
accepted value
2.5
Conclusion:
Both parts of my hypothesis were correct. Both the triple beam balance and
digitals scale gave the result that pennies made after 1982 had less mass than the pennies
made before 1982. My data also shows that the digital scale gives more precise and more
accurate data, which agrees with my original hypothesis. Although the standard
deviations for the after 1982 pennies measured by both the triple beam balance and the
digital scale were equal (both 0.025 g), the standard deviation for the before 1982 pennies
measured by the digital scale (0.0274 g) was much less than the standard deviation for the
same pennies measured by triple beam balance (0.75g). This difference between the
standard deviations shows that the digital scale gave more precise data. I know that the
digital scale gave more accurate data because the percent errors with the digital scale (0.9
% and 0.8%) were much lower than those of the triple beam balance (2.9% and 3.2%).
I believe that any error came from human mistakes or equipment defects. For
example, we had to zero our digital scale between each trial, so I don’t think it was the
best digital scale we could have used. There is also a lot of human error when using the
triple beam balance. It is difficult to move the sliders to exactly the right place, and it is
hard to read the final result in a consistent manner.
From this experiment, I learned that pennies made after 1982 have less mass than
pennies made before that date. This experiment could be improved by perhaps using a
third method to measure mass – maybe a balance scale or a more sensitive digital scale.