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e Review the Syllabus
e Notes for Lab 1
The Metric System
Objects we deal with in astronomy cover many
size scales:
Electron
e
mit}
DeTitta ey
e 5960 SS)
Pot Ft] *
i i ae Our Solar System
e :00000000005 meters ,
= .05 nanometers Pri] 5960000000000 meters
Pit ey aot e-y = 5960 Gigameters
e
Lt
e 5" 10" = 70"
Pe Mt) ey
e The metric system provides a useful notation to
cover these scales.
Changing Units ● First we need our distance conversion factor: 1 foot = 0.3 meters 10 ft sec =10 ft sec x 0.3 m ft =3 m sec The nice thing about the METRIC system is that conversion between metric units just involves powers of ten. (1000 m = 1 km) 3 m sec x 0.001 km m =0.003 km sec There is nothing special about time in the metric system. We will continue to use hours, minutes, seconds, etc. 0.003 km sec x60 sec min x 60 min hour =10.8 km hour Scale Conversion ● Now I need to know the scale on this map to learn the distance around the rings. ● Using the scale given in the bottom left corner of the image, I measure with my ruler that 100,000 km is equal to five inches. Scale Conversion, cont'd. ● This gives us a SCALE FACTOR of 1 in = 20,000 km ● I also measured the distance around the rings with my ruler to be 140 inches. ● To find the actual distance in km, I multiply my scale factor by the distance I measured on the map. 140 inches x 20,000 km inches =2,800,000 km Note, you probably will not be getting the exact answer, but you should be getting something close. Scientific Notation
« Scientific Notation is just a way to express a number with a lot of zeroes:
Distance between Sun and Earth = 1 AU = 149,000,000,000 meters
149,000,000,000 meters = 1.49 x 10' meters
« All we have to do is count how many times we move the decimal point to the first non-zero number, and write
ae koa
Size of a hydrogen atom = .000000000053 meters
,000000000053 meters = 5.3 x 10‘meters
« If we move the decimal point to the left, the blank is a positive number. If we move the decimal point to the
right, it's a negative number.
Scientific Notation + Math
Multiplication and Division with Scientific Notation:
Multiplication
(2.5 x 10”) x (5.0 x 10")
TTL eS tt A o
ae.
(2.5 x 104) x (5.0 x 104)
..Aind then add these two together.
2.5xX5.0 = 12.5
17+ 14 = 31
Division
aa
50x10"
Then subtract
Fe i 17
Just divide the bottom :
these Nee SO from the top.
et OnE aa
2.5/5.0=0.5
17-14=3
Graphing/Plotting
y=mx+b
c To graph this, we start plugging in values for "x" and see what "y" pops out:
Example: y = 2x + 1
y = 2(0) + 1
y=1
x=0O0
y =2(1) +1
y=3
PP
y=5 y
