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Astronomy > Test 1 > Flashcards

Test 1 Flashcards

0
Q

The start of the Universe’s expansion is commonly called ___ ___ ____.

A

The Big Bang

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1
Q

What is our cosmic address?

A

Earth, solar system, Milky Way Galaxy, local group, local supercluster, Universe

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2
Q

The farther away we look in the ____, the farther back we look in ____.

A

distance; time

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3
Q

Lightyears

A

The distance light can travel in one year

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4
Q

According to the Voyage Model, if the Sun was a grapefruit, the Earth would be a ____ ______. Jupiter would be a _____.

A

pen’s ballpoint; marble

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5
Q

The nearest star to the Sun is __ light years away.

A

4

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6
Q

If a light year is 1 mm, the Milky Way is the length of a _____ _____.

A

football field

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7
Q

If the time span between the Big Bang and now were a calendar, when would humans be?

A

Last 30 seconds of December 31

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8
Q

Earth’s daily rotation is…

A

how it spins on its axis

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9
Q

Earth’s orbit around the Sun is a _____.

A

revolution

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10
Q

Earth’s average orbital distance is equal to

A

1 au (astronomical unit)

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11
Q

1 au =

A

150 million km

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12
Q

Earth’s orbital path defines a flat plane called an ____ ____.

A

ecliptic plane

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13
Q

Does the solar system move in relation to other stars?

A

Yes

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14
Q

How fast does the solar system move in relation to other stars?

A

70,000 km per hour

40,000 mph

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15
Q

Virtually, every galaxy outside the Local Group is moving ____ us.

A

away from

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16
Q

Who developed the first scientific model for astronomy?

A

Ancient Greeks

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17
Q

All scientific models are subject to being _____.

A

disproved

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18
Q

Always change the ____ rather than the ____.

A

model; data

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19
Q

A scientific model requires what 3 things?

A

Geometry, Physics, Aesthetics

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20
Q

What are the 5 steps of a scientific model?

A

“Real World” -> observe nature -> Model (geometry, physics, aesthetics) -> comparative observations -> revise model to match observations

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21
Q

Does a scientific model require accuracy to qualify as a model?

A

No

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22
Q

What type of universe did Ptolemy believe in?

A

Ptolemaic System: geocentric

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23
Q

Did the Ptolemaic System qualify as a scientific model? Was it accurate?

A

Yes; No

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24
Q

uniform circular motion

A

Move in a circle at a non-varying speed

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25
Q

Aristotelian Physics

A

The natural motion of all earthy materials is to fall towards the center of the universe (Earth)

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26
Q

What are the four earthy materials in Aristotelian Physics?

A

Earth, air, fire, water

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27
Q

According to Aristotelian Physics, what are the planets/heavenly bodies made of?

A

The 5th material, quintessence

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28
Q

Greeks were obsessed with perfect _____ and _____.

A

circles; spheres

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29
Q

What three things supported the Ptolemaic System?

A

uniform circular motion, Aristotelian Physics, Greek love of perfect circles and spheres

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30
Q

Greeks believed the heavenly bodies had no ____.

A

blemishes

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31
Q

Copernicus proposed a ____ model for the universe.

A

heliocentric

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32
Q

What did Copernicus believe orbited the earth?

A

Just the moon

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33
Q

What was the Copernican System’s primary motivation?

A

Aesthetics

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34
Q

Was the Copernican System more accurate than the Ptolemaic System? Why or why not?

A

No. Held flawed belief in uniform circular motion.

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35
Q

Did the Copernican System qualify as a scientific model?

A

No, there was no physics aspect.

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36
Q

What was the geometry aspect of the Copernican System?

A

uniform circular motion

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37
Q

Was the Copernican System a better or worse scientific model than the Ptolemaic System?

A

worse

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38
Q

What did Tycho Brahe contribute to astronomy?

A

astonishingly accurate naked-eye observations

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39
Q

How were Tycho’s observations so accurate?

A

he had a giant angle-measurer

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40
Q

How accurate were Tycho’s observations?

A

within an arcminute

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41
Q

What is an arcminute?

A

1/60 of a degree

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42
Q

Did Tycho side with Ptolemy or Copernicus?

A

Ptolemy

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43
Q

Tycho’s data allowed people to _______________.

A

test the Ptolemaic and Copernican models

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44
Q

What did Galileo contribute to astronomy?

A

he invented a stronger telescope

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45
Q

Galileo began the process of finding _____ to satisfy the Copernican System.

A

physics

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46
Q

What made Kepler a better scientist than those before him?

A

He tossed out ideas if they didn’t fit the model or agree with the data.

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47
Q

Kepler tossed out ideas if they didn’t fit the ____ or agree with the ____.

A

model; data

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48
Q

Kepler was _____’s apprentice.

A

Tycho

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49
Q

Did Kepler like the Ptolemaic or Copernican System?

A

Copernican

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50
Q

What did Kepler discover?

A

elliptical orbits

51
Q

Kepler changed the ____ to fit the ____.

A

model; data

52
Q

What is an example of Kepler changing the model to fit the data?

A

He substituted an ellipse for a circle in regards to orbits.

53
Q

What is Kepler’s first Law of Planetary Motion?

A

Planets orbit the Sun in elliptical orbits with the sun at one focus.

54
Q

What is Kepler’s second Law of Planetary Motion?

A

As a planet orbits the Sun, its distance from the Sun changes. If it’s closer to the Sun, it moves faster. If it’s farther from the Sun, it moves slower.

55
Q

According to Kepler’s second law, planets mover faster when they are _____ ____ the Sun.

A

closer to

56
Q

According to Kepler’s second law, planets mover slower when they are _____ ____ the Sun.

A

farther from

57
Q

What is Kepler’s third Law of Planetary Motion?

A

There is a mathematical relation between a planet’s period (time it takes to orbit Sun) and its distance from the Sun.
p^2 = K * a^3
More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship
p^2 = a^3

58
Q

In p^2 = K * a^3, what is p?

A

p = period

59
Q

In p^2 = K * a^3, what is K?

A

K involves the mass of the Sun
with right units, K = 1, rendering it unnecessary in the equation
p^2 = a^3

60
Q

In p^2 = K * a^3, what is a?

A

a = distance between the Sun and the planet

measured in au (astronomical units)

61
Q

p^2 = K * a^3 can be used to determine the ____ of stars.

A

mass

62
Q

Kepler’s third law is the only way we have of measuring the ____ of faraway space objects.

A

mass

63
Q

How did Kepler’s model involve physics?

A

magnetic force between Sun and planets (incorrect)

64
Q

How did Kepler’s model involve geometry?

A

ellipses

65
Q

Isaac Newton built on _____’s model and _____’s data.

A

Kepler; Galileo

66
Q

What does Newtonian Physics include?

A

Three Laws of Motion and Law of Gravity

67
Q

Newton’s telescopes used ____ instead of lenses.

A

mirrors

68
Q

Newton invented what mathematical discipline?

A

calculus

69
Q

Newton’s Three Laws of Motion ____ (prove/disprove) Kepler’s Laws.

A

prove

70
Q

Newton’s Laws explain the movement of ____.

A

planets or heavenly bodies

71
Q

What is Newton’s first law?

A

Inertia. Every body continues in its state of rest or uniform motion in a straight line unless an external force acts. An object at rest tends to stay at rest, while an object in motion tends to stay in motion.

72
Q

Velocity includes ____ while speed does not.

A

direction

73
Q

acceleration

A

any change in velocity (speeding up, slowing down, changing direction)

74
Q

A negative acceleration is _____ ____.

A

slowing down

75
Q

A positive acceleration is ____ ____.

A

speeding up

76
Q

G-force happens when you’re in something accelerating ____.

A

positively

77
Q

Inertia happens when you’re in something accelerating ____.

A

negatively

78
Q

What is the difference between G-force and inertia?

A

G-force: positive acceleration

Inertia: negative acceleration

79
Q

In order to accelerate an object, you must apply __ _____ ____.

A

an external force

80
Q

Applying a perpendicular external force to an object changes ____.

A

velocity

81
Q

Applying a parallel external force to an object changes ____.

A

speed

82
Q

To change an object’s velocity, you must apply a _____ _____ force.

A

perpendicular external

83
Q

To change an object’s speed, you must apply a _____ _____ force.

A

parallel external

84
Q

When applying the same force, more massive objects accelerate ____ and less massive objects accelerate ____.

A

less; more

85
Q

What is Newton’s second law?

A 
force = m*a
force = mass * acceleration
86
Q

The rate of change of momentum of a body is proportional to ____ ______ ______.

A

the applied force

87
Q

The rate of change of momentum of a body takes place in the direction ___ _____ _____.

A

the forces takes

88
Q

What is Newton’s third law?

A

To every action, there is an equal and opposite reaction.

89
Q

What is the reaction of Earth’s gravity pulling you down toward its center?

A

you pull the Earth up with the same amount of force

90
Q

What is an example of an action/reaction pair?

A

you/Earth

Earth/Sun

91
Q

action = ?

A

action = change of momentum * distance over which momentum is changed

92
Q

Earth pulls you down and you pull Earth up with a force equal to ____ ____.

A

your weight

93
Q

Explain the fuel/rocket action/reaction pair.

A

The built up fuel pressure pushes out back of rocket, thrusting rocket up.

94
Q

What is Newton’s Law of Universal Gravitation?

A

There is a force of gravitation between any 2 objects in the universe. More massive objects have a greater gravitational force.
Force = G * [Mass(1) * Mass(2)] / (Distance)^2

95
Q

_____ is also a factor in Newton’s Law of Universal Gravitation.

A

Distance

96
Q

radius

A

the distance to the center

97
Q

Give an example of distance being a factor in Newton’s Law of Universal Gravitation.

A

You -> Earth

Earth -> Sun

98
Q

Where should you measure the distance between two objects from?

A

their centers

ex.: Earth’s center -> your bellybutton

99
Q

In Force = G * [Mass(1) * Mass(2)] / (Distance)^2, what is G?

A

gravitational constant

100
Q

In Force = G * [Mass(1) * Mass(2)] / (Distance)^2, what is the distance?

A

between the two objects’ centers

101
Q

Why don’t you fall toward other objects if there’s a gravitational force between you?

A

The gravitational force between you and the Earth is greater, because Earth has a greater mass than any object on it. Earth pulls you down.

102
Q

If the distance between two objects doubles, there’s ____ the force.

A

1/4

103
Q

If the distance between two objects triples, there’s ____ the force.

A

1/9

104
Q

If the distance between two objects is 10 times, there’s ____ the force.

A

1/100

105
Q

If an object weighs 100 N, and its distance from Earth doubles, what does it weigh now?

A

25 N (Newts)

106
Q

The moon is basically ____.

A

falling

107
Q

The more massive object has more force acting on it, thus it takes ___ force to accelerate it.

A

more

108
Q

Two objects orbiting the same object will have ___ orbital periods/speed/etc.

A

equal

109
Q

In general, for anything to move in a circular path, you have to have an inward force that’s constantly applied for a change in direction. What is this force?

A

centripetal force

110
Q

centripetal force

A

a force that acts on a body moving in a circular path and is directed toward the center around which the body is moving

111
Q

When the moon orbits Earth, ____ applies the centripetal force.

A

gravity

112
Q

If centripetal force suddenly stops, the object will…

A

go in a straight line (Newton’s first law, inertia)

113
Q

Do things fall on the moon?

A

yes

114
Q

What fraction do objects weigh on the moon compared to Earth?

A

1/6

115
Q

While falling, an object is ____.

A

weightless

116
Q

What two modifications have been made to Newton’s laws?

A 
Quantum Mechanics (atoms do not obey Newton's laws)
Einstein's Relativity
117
Q

What is the Law of Conservation of Energy?

A

total amount of energy in the universe always remains the same

118
Q

How does the Law of Conservation of Energy work?

A

different types of energy (gravitational, motion, etc) convert into one another

119
Q

Does mass affect orbital periods?

A

No

120
Q

What affects orbital periods?

A

orbital distance

121
Q

eccentricity

A

amount an ellipse is stretched compared to a circle; circles have zero eccentricity

122
Q

Why can we use Kepler’s third law to calculate a planet’s average orbital speed?

A

The law relates a planet’s orbital distance to its orbital time (period).

123
Q

How did Galileo answer the aesthetic objection to a heliocentric system?

A

Using his telescope, he proved the existence of sun spots and mountains & valleys on the moon.

124
Q

stellar parallax

A

apparent shifting of an object against a background; parallax depends on distance, nearer objects experience greater parallax than more distant objects

125
Q

What is Occam’s Razor?

A

the idea that scientists prefer the simpler or more aesthetically pleasing of two otherwise equal models

Astronomy (5 decks)

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