Lab 1: Measurement Lab
Objectives:
1. To determine the accuracy and precision of various estimates of length.
2. To use water displacement and a mass balance to determine the density of
various objects.
3. To determine the identity of the mystery substance from its density.
Introduction
Terms:
Accuracy - a measure of how close a measurement is to some accepted, true value
Precision - a term used to describe how close repeated measurements are to each
other
Mass (m) – a measure of the amount of material that an object contains
Volume (V)–the space occupied by an object
Density () –the ratio of an object’s mass to its volume
𝑚𝑎𝑠𝑠
𝑚
𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =
=𝜌=
𝑣𝑜𝑙𝑢𝑚𝑒
𝑉
Part I: Accuracy and Precision
1. Tear a sheet of computer paper into eight (8) equal size rectangles.
2. Without a ruler, draw a free hand line that you estimate to be 5.00 cm long
on one of the sheets. Turn the sheet of paper over so you don’t see it.
3. Repeat drawing of what you estimate to be 5.00 cm long lines on three (3)
more sheets of paper, each time turning the sheet over so that you are
drawing a line without being able to look at your previous estimates.
4. Get a metric ruler (you can download an app if you don’t have a physical
ruler) and measure each of the four lengths. Enter these measurements in
the data table below. These measurements should have (two) 2 digits to the
right of the decimal point. For example, 5.48 cm instead of 5.5 cm or 5 cm.
5. Set aside (face down) the first four sheets. Repeat the above process with
the remaining 4 pieces of paper, each time turning them over so that you
cannot see the other estimates. Each student should have his/her own data
set (replace student number in the table with actual name). The table shown
is for two students. Copy and paste to add more tables if needed.
6. Calculate the average (mean) value by adding the four measurements and
dividing by 4.
7. To determine if a value is accurate, compare it to the accepted value.
Calculate for the percentage error using the formula shown. The accepted
length is 5.00 cm. Note that a percentage error should be an absolute value.
% 𝐸𝑟𝑟𝑜𝑟 = |
𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑙𝑒𝑛𝑔𝑡ℎ − 𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑙𝑒𝑛𝑔𝑡ℎ
| 𝑥 100
𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑙𝑒𝑛𝑔𝑡ℎ
8. To determine if a value is precise, find the average of your data then subtract
each measurement from it. This gives you a table of deviations. Then
average the deviations (M.A.D.). This will give you the uncertainty - a plus
or minus value that says how precise a measurement is.
𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 = |𝑎𝑣𝑒𝑟𝑎𝑔𝑒 − 𝑎𝑐𝑡𝑢𝑎𝑙|
𝑚𝑒𝑎𝑛 𝑎𝑏𝑠𝑜𝑙𝑢𝑡𝑒 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛 (𝑀. 𝐴. 𝐷. ) =
J.Regalado/03/19/21
𝑠𝑢𝑚 𝑜𝑓 𝑎𝑙𝑙 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛𝑠
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑚𝑒𝑛𝑡𝑠
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Part 1 Tables:
Trials:
student
1
Measured
length
(cm)
1
2
3
4
--Ave:____
Trials: Measured
student
length
1
(cm)
5
6
7
8
--Ave:____
%
Error
%
Error
Deviation
MAD: __
Deviation
MAD: __
Trials: Measured % Error Deviation
student
length
2
(cm)
1
2
3
4
--Ave:____
MAD: __
Trials: Measured % Error Deviation
student
length
2
(cm)
5
6
7
8
--Ave:____
MAD: __
Questions:
1. For each student, which of your two sets of estimates - (trials 1-4) and (trials
5-8) was more accurate? Justify your answer.
2. For each student, which of your two sets of estimates - (trials 1-4) and (trials
5-8) was more precise? Again, justify your answer.
3. Is the most accurate set also the most precise? Do they have to be? Explain.
Part II: Density
1. Navigate to the Density Lab (opens in a new window) website.
Plain Text Link https://unctv.pbslearningmedia.org/resource/arct15-scidensitylab/density-lab/
2. Launch the simulation. Click on “Turn Fluid into water”. Record the fluid
density for water on the table.
3. Select gold. Record the final volume when the object is submerged in the
fluid.
4. Grab the object and drop it in the scale. Record its mass in grams.
5. Record the initial water level.
6. Calculate for the object’s volume using the fluid displacement method. The
difference between the final and initial fluid volume is equal to the volume of
the fully submerged object.
7. Calculate for the density of the object using the formula below:
𝑚𝑎𝑠𝑠 (𝑔)
𝑑𝑒𝑛𝑠𝑖𝑡𝑦 = 𝑣𝑜𝑙𝑢𝑚𝑒 (𝑚𝐿)
8. Repeat steps 1 -6 for iron, lead, and the mystery object. Record all data in
the table.
9. Reset the sim. Select wood. Move the slider to adjust the fluid density so that
the wood sinks to the bottom. Record the fluid density.
J.Regalado/03/19/21
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10.Record the final volume when the object is submerged in the fluid.
11.Grab the object and drop it in the scale. Record its mass in grams.
12.Record the initial water level.
13.Calculate for the object’s volume using the fluid displacement method. The
difference between the final and initial fluid volume is equal to the volume of
the fully submerged object.
14.Calculate for the density of the object using the formula below:
𝑔
𝑚𝑎𝑠𝑠 𝑖𝑛 𝑔
𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑖𝑛 𝑚 : = 𝑣𝑜𝑙𝑢𝑚𝑒 𝑖𝑛 𝑚𝐿
15.Repeat steps 8-13 for foam and rubber. Record all data in the table below.
Part 2 Table:
Trial
Mass
(g)
gold
iron
lead
wood
foam
rubber
mystery
Fluid density
Fluid density
Fluid density
Fluid density
for
for
for
for
the
the
the
the
Initial Vol.
(mL)
Final Vol.
(mL)
Object Volume
(final – initial)
mL
Density
(g/mL)
gold, iron, lead trials= _1 g/mL_
wood trial= _____
foam trial= _____
rubber trial= _____
Questions:
1. Which object has the highest density? The lowest density?
2. Use your data to explain why gold, iron, and lead, sank in water.
3. Use your data to explain why wood, foam, and rubber, did not sink in water.
4. Fully explain why the fluid density had to be changed for wood, foam, and
lead in the context of finding their densities.
5. What is the mystery material? To identify the mystery material, go online
and find the closest density value matching your measured value.
Conclusion:
Write a conclusion that addresses the objectives. Indicate at least three (3) lessons
learned. Include a discussion of possible sources or error and suggestions to
improve the results.
J.Regalado/03/19/21
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