Puzzling Parallax
A Science Fair Project
By
Z
January, 2013
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Abstract
The purpose was to see the effect of viewing positions on
how the object being viewed appears to move relative to a
distant object, and the hypotheses was if an object is viewed
from a more distant position, then it will appear to move
more than when viewed from a closer point. My hypothesis
was proven wrong by the difference decreasing instead of
increasing.
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Table of Contents
Title Page ……………………………………………………………………………..1
Abstract ……………………………………………………………………………....2
Introduction …………………………………………………………….…………..4
Problem ………………………………………………………….…………….4
Hypothesis ……………………………………………………….…………..4
Independent Variable …………………………………………………..4
Dependent Variable …..…………………………………………………4
Constants or Controlled Variable .…………………………………4
Background Research …………………………………………….......5
List of Materials ...……………………………………………………...………..6
Experimental Procedure ………………………………………………………7
Data Table ………………………………………………………………………….10
Graphs ……………………………………………………………………………….11
Data Analysis ……………………………………………………………………..11
Conclusion …………………………………………………………….……………12
Bibliography ………………………………………………….…………………...14
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Introduction
Topic: Puzzling Parallax
Problem Statement: What is the effect of the distance between
two objects on how the distant object to shift when observed
from two locations?
Purpose: To investigate how an object appears to move when
viewed from different distances.
Hypothesis: If the distance between two objects is decreased,
then the far object will appear to move or shift more when
viewed from two positions.
Independent Variable: Distance between the near object and
the observation point.
Dependent Variable: How much the object shifts at each
viewing distance
Constants:
 Same distant object
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 Same near object
 Same observation locations (Hula Hoops)
 Same experimental set-up
 Same measurement tool
Number of Trials: 1
List of Materials:
 Meter stick
 Measuring tape
 2 Hula hoops
 Long stick (3 feet)
 2 Thick rubber bands
 Coffee can
 Gravel
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Background Research
According to Bing dictionary, parallax is an apparent change in
the position of an object when the person looking at the object
changes position. At different times of the year, the earth is at
different positions in its orbit around the sun. The near stars
look like they move relative to more distant stars. This is called
parallax. Astronomers use parallax to measure the distances of
planets, stars and galaxies. It can be observed by lining one
finger close to the face in between the eyes and looking at any
object in front of you. Close one eye and observe the position
of the object.
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Experimental Procedure
1. Attach a meter stick at the end of a long stick of about 3
feet using a rubber band. It should look like an “L”.
2. Fill a coffee can with gravel to weigh it down and use it to
anchor the stick in such away the end with the meter stick
is at the top,
3. Carry the set-up to the gym where there is a wide space
and place it at one end. The stick in the can will serve as
the near object.
4. Facing the set-up, place two hula hoops on your left and
right side. The centers of the hula hoop will serve as the
two viewing positions.
5. Have a volunteer stand at the other end of the gym
directly opposite the set-up.
6. Work three to five steps towards the distant object and
place the apparatus on the floor with the yard stick facing
the hula hoops.
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7. Using the measuring tape, measure the distance between
the hula hoops and the set-up and record it on the data
table.
8. Sit in the center of the left hula hoop and look at the
distant object. Find the number on the meter stick that
lines up with the distant object. Write the number in the
data table.
9. Repeat step 8 with the hula hoop on the right.
10.
Repeat steps 6 – 9 for four more times.
11.
For each viewing distance, calculate the difference
between the measurements from the left and right hula
hoops and write it in the data table.
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The Set-up for Observing and Measuring Parallax
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Data Table
Levels of
Independent
Variable
Number on
Ruler that
lines Up
from Left
Hoop
Number on Difference
Ruler that or Measure
lines Up
of Shift (cm)
from Right
Hoop
Number
of Steps
from
Near
Object
Distance
from
Near
Object
(inches)
4
91
11
14
3
7
170
17
14
3
11
274
18
19
1
14
347
19
18
1
10
17
430
18
18
0
Difference in Position
from thenTwo
Observation Points (In)
Shift in Observation with Change in Distance
3.5
3
2.5
2
1.5
1
0.5
0
0
100
200
300
400
500
Distance from Observation Points to Near Objects (In)
Data Analysis and Discussion
At a distance of 91 inches between the near object (the
pole/yard stick set-up) observation point, the observation of
the distant object lined up with 11 cm on the meter stick when
viewed from the left hula hoop and 14 cm from the right hula
hoop. Hence the difference or shift was 3 cm. At 170 inches
distance the difference or shift was also 3. At 274 inch and 347
inch distances, the difference or shift was 1 cm each. And for
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the longest viewing distance of 430 inches investigated, the
difference or shift was 0 cm.
Conclusion
The hypothesis was that if the distance between two objects is
decreased, then the far object will appear to move or shift
more when viewed from two different positions. Looking at the
results of the experiment, when the near object was moved 91
inches closer to the far object, and when moved 170 inches
closer, the difference or shift in the position of the far object
being viewed were the 3 cm each. There was no difference in
the two results. When they were moved 274 and 374 inches
closer to the distant object, the shift in the far object’s position
decreased to 1 cm in each case. Then it decreased to 0 cm
when moved 430 inches closer. The hypothesis was not
supported by the data because the shift in the position of the
far object decreased overall from 3 cm to 0cm as the distance
between the objects decreased. The hypothesis was that if the
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distance between two objects is decreased, then the far object
will appear to move or shift more when viewed from two
positions. Instead the far object moved or shifted less as the
distance between them decreased.
Ideas for Further Research
It was difficult seeing clearly the number on the yard stick that
lined up with the distant object as that the near object with the
yard stick was moved farther away from the viewing position
and closer to the distant object. It may have affected the
results. It will be better to use a yard stick with bolder numbers
to repeat the experiment and see what the result will be.
Acknowledgement
Mrs. Chukwu
Mr. Harris
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Bibliography
http://www.sciencebuddies.org/science-fairprojects/project_ideas/Astro_p006.shtml
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