a 1020 template study guide 1 scinot_angles0

7/29/2019 A 1020 Template Study Guide 1 Scinot_Angles0

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ASTR 1020 Study Guide 1

Stellar and Galactic Astronomy

Scientific Notation and AnglesReview


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How to Use the Study Guide

Study Guide is the framework for the contentof this class Contains the selection of topics

Provides sequence of topics Indicates depth of topics

Includes relevant practice questions andexercises

Omit material in textbook that is not referred to bystudy guide *

Dont go into more depth or detail than indicatedby the study guide *

*


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Scientific Notation & Angles - I

Astronomy

Physical science of planets (including Earth),stars (including Sun), and everything else in

space Investigate with scientific method

Deals with astronomically large numbers Age of universe: 13 15 billion years

Number of stars in a galaxy: 100 billion Deals with miniscule, tiny numbers

Size of atomic nucleus: 0.000000000000001 m

Number of atoms in a cubic meter of space:

0.00001


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Scientific Notation & Angles - II

Review of Scientific Notation

Use positive exponents of 10 for numbers >

1 or prefixes

1 thousand = kilo = 1,000 =

103

1 million = Mega = 1,000,000 = 106

1 billion = Giga = 1,000,000,000 = 109

1 trillion = Tera = 1,000,000,000,000 = 1012


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Scientific Notation & Angles - III

Use negative exponents of 10 for numbers 1

367,000 = 3.67 x 105

Ex: regular decimal < 1 0.0000367 = 3.67 x 10-5

Review UNL class action outline Scientific Notation

Go over UNL class action questions Scientific Notation,

Calculation in Scientific Notation
http://astro.unl.edu/classaction/outlines/intro/sci_not.htmlhttp://astro.unl.edu/classaction/questions/intro/ca_intro_scientnot.htmlhttp://astro.unl.edu/classaction/questions/intro/ca_intro_calcscientnot.htmlhttp://astro.unl.edu/classaction/questions/intro/ca_intro_calcscientnot.htmlhttp://astro.unl.edu/classaction/questions/intro/ca_intro_scientnot.htmlhttp://astro.unl.edu/classaction/outlines/intro/sci_not.html


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Scientific Notation & Angles -

Practice 1- I

Conversions:

convert to scientific notation:

a. 0.00089 b. 5341 convert to decimal form:

c. 4.31 x 102 d. 7.3 x 10-5

Which of the following is smaller e. 6.42 x 10-4 or 1.26 x 10-3

f. 6.42 x 104 or 1.26 x 103


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Practice 1- II

The number 0.008166 in scientific notation

would be

a. 8.166 x 10 -3

b. 8.166 x 10 -2

c. 8.166 x 10 -4

d. 8.166 x 102

e. 8.166 x 10 3


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Scientific Notation & Angles

Answers 1-I

a. 8.9 x 10-4 d. 0.000073

b. 5.341 x 103

e. 6.42 x 10-4

c. 431. f. 1.26 x 103


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Answers1- II

The original number is < 1 so the exponent

will be negative. The decimal point has to

be moved 3 places to make a decimal

number with one digit in front of thedecimal point. That means the correct

answer is a) 8.166 x 10-3


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Scientific Notation & Angles - VAngles Review

The night sky appearsspherical to us soastronomy uses angles

to measure positions andsizes of objects

Definition: An angle is the exact measure ofthe opening between two connecting straight

lines

UNL Class Action Fist Angle Diagram


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Scientific Notation & Angles - VI

Examples:

Right Angle = 90 = /2 rad

Straight Line = 180 = rad

Complete Circle= 360 = 2 rad


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Scientific Notation & Angles - VII

Very small angles may be used in Astronomy

Degree breaks into arcminutes andarcseconds

1= 60 arcmin = 60'

1' = 60 arcsec = 60 Ex: Full Moon subtends = 30' in the sky Review UNL class action outlineAngular

Measurements

How small is 1' ? The width of a dime (about 1 cm) seen from thedistance of a little over 1 mile (about 2 km)!

Play around with UNLs Small Angle Demonstrator Does smallest object at largest distance get close to 1 arcsec?

Go over UNL class action questionsAngular Diameter Mobile,

i tifi N t ti & A l
http://astro.unl.edu/classaction/outlines/coordsmotion/ang_meas.htmlhttp://astro.unl.edu/classaction/outlines/coordsmotion/ang_meas.htmlhttp://astro.unl.edu/classaction/animations/intro/smallangledemo.htmlhttp://astro.unl.edu/classaction/questions/ancientastro/ca_ancientastro_angulardiametermobile.htmlhttp://astro.unl.edu/classaction/questions/ancientastro/ca_ancientastro_angulardiameterballoon.htmlhttp://astro.unl.edu/classaction/questions/ancientastro/ca_ancientastro_angulardiametermobile.htmlhttp://astro.unl.edu/classaction/animations/intro/smallangledemo.htmlhttp://astro.unl.edu/classaction/outlines/coordsmotion/ang_meas.htmlhttp://astro.unl.edu/classaction/outlines/coordsmotion/ang_meas.html


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cientific Notation & Angles -VIII

University of Nebraska Lincoln Class Action Images


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Practice 1- III

a) How many arcseconds are in 1?

b) The width of your thumbnail at your

outstretched arm also equals the angle of the

full Moon. In outstretched thumbnail units, whatangle does a half Moon subtend during first or

last quarter phase?

c) How many arcseconds does a half Moonsubtend?

d) If you bring your thumb closer to your eyes,

does the rule in b) still hold? Explain.


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Practice 1- IV

Angles are measured in such a way that theangle of a straight line is:

a. 90 degrees

b. 2 radians

c. 180 degrees

d. /2 radians

e. 360 degrees

S i tifi N t ti & A l


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Answers 1- III

a) 1= 1(60/1)(60/1) = 3600 b) During the first or last quarter lunar phase,

exactly half of the sunlit side of the Moon isvisible = a full Moon = thumbnail width.

c) convert b)s answer to arcseconds: thumbnail width = 15 (60/1) = 900"

d) No, with the thumb closer to the eyes, the nail

subtends an angle greater than the full moon. e) Yes, because most peoples body proportions

are proportional to their height. So, people thatare that much taller have that much longer arms

and bigger hands.


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Answer 1- IV

The correct answer is c) 180 is the angle

spanned by a straight line.

The other choices are wrong for the

following reasons: 90 is the a right angle

where two lines come togetherperpendicularly; /2 radians is also a right

angle. Likewise, 360 and 2 radians arethe angles contained in a full circle.

a 1020 template study guide 1 scinot_angles0

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