Purpose
Students will us vector addition on
the Flat-Earth Model.
Theory
Vector addition is easy and useful.
To add (24,0) to (0,-7), the 1st numbers
are added, as are the 2nd, and the order
stays the same: (24,-7). These can be x-
and y-positions, velocities, forces, etc.
Which way are the streaks on the
side windows of a car going 24 MPH if
driving through rain falling at 7 MPH?
That's a vector of (24,-7). The angle is
found by taking the arctangent of the
second 2nd over the 1st: tan¹(-4)=16⁰.
The Flat-Earth Model claims earth
is a horizontal disk. The north pole is at
the center, "Antarctica" is a rim wall at
the edge, and the sun and moon move
in circular paths above the disk. If true,
it should be easy to measure the sun's
altitude and make predictions.
Procedure
1. Find a cardboard box about the size
of a microwave, cut off the top flaps,
and set it on its side outdoors at noon.
2. Cut a coffee-cup-sized hole in the
middle of the upper wall and tape a
sheet of aluminum foil over it. Poke a
small hole in that with a pin or tack.
3 With the sun overhead, even if it is
slightly cloudy, a spot of light should
show on the bottom surface in the box.
Propping the box at a tilted angle may
be necessary, but then don't move it.
Mark the box bottom where the spot is
at noon, and then again at 1PM.
4. Find a ruler and measure the height
from the noon mark up to the foil hole.
Let this be y. Also measure the distance
between the marks. Let this be x. Units
can be inches, centimeters, whatever.
The sun's ray vector in the box is (x,y).
This vector can also be used to find the
sun's angle above the horizon.
Figure 02: The box as described.
5. The sun apparently moves 1000 mi
in an hour. (Call someone in Ft. Worth
and ask them what time of day the sun
is highest in the sky, if skeptical.) The
sun's height in miles is h = 1000-y/x.
6 If the Flat-Earth model is right, the
sun always keeps this height, so after
seven hours, the spot goes 7-x laterally.
Find the predicted sun angle above the
horizon at 7 PM using tan-¹(). Wait
for 7 PM and see if that's nearly right.
Analysis
Please answer each of the following
in Canvas using complete sentences:
1. How high up (h) is the sun using the
Flat-Earth Model?
2. At what angle above the horizon is
the sun at 10 PM using this model?
3. What is the diagonal distance to the
sun at 10 PM by this model when its
position vector is (10000,h) miles?
4. Did this lab disprove all unpopular
scientific viewpoints? Why or why not?



* I’ve already found my sun’s ray vector in the box which was (4.25, 17.25). *