PHYS 100 EXPERIMENT 4 (week 5)
Logger Pro
Name: _______________________ Student #: _____________ Section: ____ Date: __________
Overview:
- Introduction (5 min)
- Exploration (20 min)
- Planning (10 min)
- Measurements (30 min)
- Agreement (15 min)
Introduction (5 min, entire class)
So far we have collected data using everyday equipment and analyzed it in a variety of
ways (histograms, SD).
Today we will learn to use lab equipment and find its effect on the measurements and
their accuracy. We will also learn to calculate agreement. At home we began working
with pendulums. Today we will explore pendulums a bit further.
Make sure in advance
that Logger Pro works
and that you know how
to use it.
☞Clicker 1: What is the formula for SD?
a. 𝑆𝐷 =
b. 𝑆𝐷 =
c. 𝑆𝐷 =
d. 𝑆𝐷 =
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e. Not sure or can’t remember Topic:
Using lab equipment to improve quality of measurements; calculating agreement.
Tasks
Task 1: Exploration (20 min, in pairs)
Today we will use Logger Pro (LP) to measure the oscillation time of a pendulum with
different weights or lengths, and see whether our measurements agree.
On the bench you can see pendulums, and a motion sensor. On your computer you
have Logger Pro, a software that reads the motion sensor.
P100 Expt.4, Fall 2012, University of British Columbia
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Explain students how to
use LP.
-show how to measure
(press “collect”).
- show how to find time
on the graph.
First, the TA will explain you how to use LP.
When the TA is done, play a bit with LP and make sure that you understand how to
read the output graph.
Encourage them to
experiment with it, see
how the output looks
like, etc. Choose where
to put the motion
detector.
Task 2: Planning (10 minutes, in pairs)
Next you will collect data that will help you answer a research question about
pendulums. Option 1 is to evaluate the same research question that you address at
home: Does length or weight of the pendulum affect its oscillation time? Option 2 is to
evaluate whether the initial angle of the pendulum affects its oscillation time.
Walk between groups
and make sure they
understand how to
measure oscillation
time.
Answer the following questions before you begin measuring:
2.1 How can you measure oscillation time? Where would you put the sensor? Try it
and describe your procedure here:
2.2. How are you going to minimize uncertainties?
2.3. Describe your measurement plan here:
a. What factor are you going to test? (either the factor you measured at home or
initial angle).
b. How many experimental designs are you going to use? How will you determine
what height, weight, or angle to use in each of them?
c. How will you determine average oscillation time? How many measurements
will you take, and how long will each measurement be?
P100 Expt.4, Fall 2012, University of British Columbia
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You can talk with
students about the
advantage of few long
measurements,
compared with more
short measurements.
Task 3: Measurements (30 min, in pairs)
Execute your measurement plan and write down your raw data.
Make sure students
repeat measurements
more than once.
Students often erase old
data, or compile it in
their heads. Emphasize
that all trials should be
well documented to be
able to make sense of
them.
Now calculate the mean and SD from your experiment.
3.1. In order to evaluate the effect of your chosen factor, how many means and SDs do
you need to calculate? (for example, one per experimental design, or one for the entire
data?)
3.2. Write your mean(s) and SD(s) here:
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Task 4: agreement calculations (15 min, in pairs)
Even if the factor that you chose has no effect on oscillation
time, it is unlikely that
Agree
you will receive exactly the same average twice. Thus, it is of interest to measure the
agreement between the methods.
Finding agreement includes two steps:
1. Find a likely range for the “true value”. This range is (mean – SD) to (mean +
x1
x2
SD)
2. If the two ranges overlap, then there is agreement between the two sets of data.
Otherwise, the two sets do not agree with each other.
Agree
x1
Disagree
x1
x2
x2
For example, if the mean of one data set is 2sec and the SD is 0.5sec, and for the other
data set the mean is 2.2sec and the SD is .4sec, we say that the two sets agree, since:
Data set 1: 1.5-2.5sec; data set 2: 1.8-2.6sec.
Disagree
The two data
sets overlap considerably, and thus we cannot say that there is a real
difference between them. Thus, they are “in agreement”.
☞Clickerx4.1: Whatxis the length of the arrows above?
2
a. SD 1
b. Range
c. 2*SD
d. (mean+SD) + (mean-SD)
The answer is (c)
The answer is (a).
☞Clicker 4.2: Why do we use (mean ± SD) instead of range?
e. Since the range depends on the extreme values and ignores everything else.
f. Since this is derived from sophisticated statistics.
g. Since the range may be too wide, and thus will give us too many agreements.
h. Other
P100 Expt.4, Fall 2012, University of British Columbia
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☞Clicker 4.3. Let us assume that your two data sets are in agreement. What does it
mean?
a. The tested factor does not affect oscillation time. b. The experiment did not find that the factor affects oscillation time.
c. The effect of the factor on oscillation time is very small.
d. Sometimes the factor affects oscillation time, but not always.
e. Not sure, I still don’t understand what agreement means.
The answer is (c). Sets 2
and 3 agree even
though the overlap in
their ranges does not
include their means.
☞Clicker 4.4: Here are three sets of data:
set 1: mean = 13; SD = 2
set 2: mean = 11; SD = 3
set 3: mean = 16; SD = 2
Which of the following statements is correct about Set 1:
a. Set 1 agrees with Set 2 but not with Set 3
b. Set 1 agrees with Set 3 but not with Set 2.
c. Set 1 agrees with both Set 2 and Set 3
d. Set 1 disagrees with both Set 2 and Set 3
P100 Expt.4, Fall 2012, University of British Columbia
The right answer is (b).
We don't know for sure
whether the factor
affects or not, since
perhaps our experiment
is not sensitive enough.
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PHYS 100 Homework 4 (for week 6)
Agreement
Name: _______________________ Student #: _____________ Section: ____ Date: __________
Goal
Finish agreement calculations from the lab.
Task
Report the following aspects of your experiment:
- How did you measure oscillation time? - Raw data (use the other side if needed) - Mean and SD for each experimental set-­‐up: - What is the range of each set of results: (mean – SD) to (mean + SD): - What portion of the measurements appear within range? Why are there results that are outside the range? - Do the two sets of results agree (that is, have partial overlap)? Why or why not? - Compare the SDs you obtained in the lab to those for the data you collected at home for the previous HW. Which is smaller? Why? P100 Expt.4, Fall 2012, University of British Columbia
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Rubric
Sufficient (✓)
Experimental design is valid
Sufficient high-quality data was collected
Mean and SD are correct
Ranges are correct; agreement is explained
well.
SDs from lab are compared to previous HW
SD, and differences are explained.
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Lacking (⍻)
Insufficient (x)
Clicker resource page:
☞Clicker 1: What is the formula for SD?
a. 𝑆𝐷 =
b. 𝑆𝐷 =
c. 𝑆𝐷 =
d. 𝑆𝐷 =
!! !!
!
!! !! !
!
!! !! !
!
!! !!
!
e. Not sure or can’t remember ☞Clicker 4.1: What is the length of the arrows above?
a. SD
b. Range
c. 2*SD
d. (mean+SD) + (mean-SD)
☞Clicker 4.2: Why do we use (mean ± SD) instead of range?
a. Since the range depends on the extreme values and ignores everything else.
b. Since this is derived from sophisticated statistics.
c. Since the range may be too wide, and thus will give us too many agreements.
d. Other
☞Clicker 4.3. Let us assume that your two data sets are in agreement. What does it mean?
a. The tested factor does not affect oscillation time. b. The experiment did not find that the factor affects oscillation time.
c. The effect of the factor on oscillation time is very small.
d. Sometimes the factor affects oscillation time, but not always.
e. Not sure, I still don’t understand what agreement means.
☞Clicker 4.4: Here are three sets of data:
set 1: mean = 13; SD = 2
set 2: mean = 11; SD = 3
set 3: mean = 16; SD = 2
Which of the following statements is correct about Set 1:
a. Set 1 agrees with Set 2 but not with Set 3
b. Set 1 agrees with Set 3 but not with Set 2.
c. Set 1 agrees with both Set 2 and Set 3
d. Set 1 disagrees with both Set 2 and Set 3
P100 Expt.4, Fall 2012, University of British Columbia
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