Physics 104
Laboratory 1 - Measurements
General Instructions: Each group should have only 3 persons.
Activity 1 – Errors in measurements
You should have already read articles that were provided to you online on the class webpage. Answer the
following questions.
1) Consider the following situation. A meter stick is used to read distances to a precision of ±1mm . The
meter stick is used to measure the length of a piece of metal with the following result: 1.735m.
a) What is the absolute error of the above measurement?
b) What is the relative error of the above measurement expressed as a percentage? Show you
calculation.
2) Two scientists experimentally arrive at values of a constant. One is 6.217 and the other is 6.289. What
is the percent difference between these experimental determinations? Show your work.
Activity 2 - Making Predictions
Predict and calculate the circumference of a circle (say a coin).
1. Experiment 1: Choose any coin. Predict the circumference in centimeters by looking at it.
Coin:__________________ Circumference: __________ cm
2. Experiment 2: use a small ruler to make the necessary measurement and do the calculations.
State which coin you used and predict the circumference of the coin. Show your calculations.
Coin:__________________ Circumference: __________ cm
3. Experiment 3: Use the same coin as in experiment 1. Make the necessary measurements using
Calipers and compare your results with experiment one. Learn how to use the Calipers. What is the
zero error and the least error of the Calipers.
Coin:__________________ Circumference: __________ cm
4. Find the percent error between Experiments 1 and 2, 2 and 3 and 1 and 3.
Percent Error (1&2): _________ Percent Error (1&3): _________ Percent Error (2&3): _________
Activity 3 – Expressing results
Roll a small ball off the edge of a table. Measure how far it lands on the floor. Make several
measurements about 15, 17 or 19 but not 12, 16 or 16 (why not?). Collect the data in a table like
Trial
Measurements in meters
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…
Find the average value ( x ) and the standard deviation (σ) (see glossary for the Lab material on class
web page). Express your results as x ± σ .
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Activity 3 – Electronic Sensors and Computer Interface: Introduction to DataStudio
Goal & Objectives: During your introductory physics labs in this semester, you will often be using an
inquiry-oriented approach where you, the student, make decisions about how to design an experiment,
collect and interpret data, and draw and report conclusions. Before most students are ready to do this
however, they need to have some sort of “bridging” activity that helps them to understand generic
experimental design. That is the focus of this laboratory activity, and as such this activity cannot be
considered inquiry oriented. The goal of this “paradigm lab” is to help you understand the nature of the
experimental process so that you are more fully capable of using this approach in the future. At the
conclusion of this lab activity, the student should be able to clearly and accurately:
• Design, conduct, and evaluate a simple experiment.
• Collect data using DataStudio.
• Interpret data using Graphs
Getting to Know DataStudio
1) Explore the DataStudio Software. You should look at the online help in the software to familiarize
yourself with DataStudio. Spend as much time as you need, because in the lab exam you will be
expected to know how to use the equipment.
2) Learn how to Interface the Photogate sensors. Investigate how you will connect this sensor, what will
it do for you and how to set up the initial parameters for it.
3) Use the PASCO Track, Cart, picket fence, Photogate, science interface box (500 or 750) and the
DataStudio software on the computer to design simple motion experiments. For example you can find
what the velocity of the cart is as you gently push the Cart from a known distance and as it passes
through the Photogate.
4) After finishing the experiment think about how to write a report. As an example, a lab report may
contain the following sections; Objective, equipment, Theory; Procedure, Data, Calculations, Graphs,
Results, sources of errors etc. The following questions might help you with the report.
a) What is the purpose of the experiment you are designing?
b) What equipment did you use?
c) What is the basic equation to calculate the quantity you are designing the experiment for?
d) How did you connect the sensor with the computer? Explain the function of sensor, the interface,
and the computer?
e) How did you conduct the experiment to collect the data?
f) What data did you obtain? Give a table
g) Explain what you can do with this data? Plot a graph to support your results.
h) Express your results. Is there a need to calculate uncertainty in the results why or why not?
i) What kinds of experimental errors (other than human errors) may have to be kept in mind for this
experiment that will affect the results?
j) How would one know that there are errors in the results?
k) Would it make sense to calculate percentage error, why or why not?
Activity 4
Use the PACO setup to find the velocity and acceleration of the cart using the photogates when the track
is inclining with at some arbitrary angle. Write a report that documents this activity.
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