AY Exam 1

What are the features of the Ptolemy's Geocentric Model?

- Earth is at the center - Sun orbits Earth - Planets orbit on small circles (epicycles) whose centers orbit the Earth on larger circles

On the cosmic calendar, when did modern humans appear?

1-2 minutes before midnight on December 31st

Out current best estimate of the age of the Universe is about ________.

14 billion years

How long is a lunar "day". That is, what is the length of time for the Moon to rotate once?

29.5 Earth days

All objects on Earth accelerate toward Earth at the same rate (neglecting air resistance) of 10 meters per second per second. If you drop an object from a tall building, how fast will it be falling after 3 seconds (that is, what is the object's velocity after 3 seconds of falling)?

30 m/s

How far away is the nearest star (if the Milky Way Galaxy is the size of a football stadium and the Sun is at the 25 yard line)?

4 millimeters away

Suppose your mass is 60 kg on Earth. On the Moon what would be your mass?

60kg

Which of the following situations is a good example of mass-energy conversion?

A small amount of the hydrogen in a nuclear bomb becomes energy as fusion converts the hydrogen to helium.

Of the following which is false about a scientific theory?

A theory is essentially an educated guess.

A planet has its greatest angular momentum around the Sun when

Actually, the angular momentum of the planet is the same no matter where it is in its orbit around the Sun

Which of the following statement is true?

All objects on Earth fall to Earth at the same rate (neglecting air resistance).

According to Kepler's second law, Jupiter will be traveling most slowly around the Sun when at ______-

Aphelion

Isotopes

Atoms with the same # of protons but different # of neutrons

Light is....

Both a wave and a particle

We saw in class that Earth is slightly farther away from the Sun in July than it is in January. How does the area swept out by Earth's orbit around the Sun during the 31 days of July compare to the area swept out during the 31 days of January?

Both areas are the same.

If you are on the Moon and have both a 10-pound and 5 pound weight, what will happen if you drop both of these weights at the same time from the same height?

Both will hit the ground at the same time.

Consider a rocket being launched upwards. Which of the following statements best describes why the rocket goes up?

By expelling gas downwards, the rocket is propelled upwards due to Newton's 3rd Law of Motion.

Protons

Carry positive charge in nucleus

An apple contains _________________ energy that your body can convert into other forms energy.

Chemical potential

The center of mass between two gravitating objects is

Closer to the more massive object

Tycho Brahe

Compiled the most accurate naked eye measurements ever made of planetary positions

What does the thermal spectrum of a solid look like?

Continuous and unbroken over a range of wavelengths

If you take the spectrum of a hot, solid object (such as a rock or a piece of metal), what will it look like?

Continuous over a broad range of wave lengths.

We saw in class that the Sun-centered model of Copernicus did not predict the motions of the planets any better than the Earth-centered model of Ptolemy. Why was this?

Copernicus used perfect circles for the orbits of the planets.

Imagine a comet that orbits the Sun on a highly elliptical path with an average (semimajor axis) distance of 1 AU. How long does it take to complete each orbit, and how can you tell?

Each orbit takes 1 year, which we know from Kepler's third law.

What is our cosmic address

Earth -> Solar System -> Milky Way Galaxy -> Local Group of Galaxies -> Universe

Is the gravitational force that Earth exerts on you larger, smaller, or the same as the force you exert on it?

Earth and you exert equal and opposite forces on each other

When we observe Mars to exhibit apparent retrograde motion in Earth's sky, what is really happening?

Earth is catching up with and passing by Mars in their respective orbits.

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July.

An astronomical unit is

Earth's average distance from the Sun.

Given the gravity law we studied in class, what would you predict would happen to Earth if the Sun were somehow replaced by a black hole of the same mass as the Sun?

Earth's orbit would not change.

Our "cosmic address" from small to large is __________

Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe;

The extent to which Mars' orbit differs from a perfect circle is called its _____________

Eccentricity

Earth orbits in the shape of a/an _________ around the Sun.

Ellipse

Earth is located at one _______ of the Moon's orbit.

Focus

If you see the Sun just setting in the west, and the Moon is just rising in the east, what phase must it be in?

Full

When do lunar eclipse occur?

Full moon

An asteroid that is moving farther from the Sun is gaining _________________ energy.

Gravitational potential

Which two of the following are isotopes of each other

Helium-3 and Helium-4

How far away is the nearest star if the Sun is the size of a grapefruit in Washington DC

In California

Suppose on a given day at noon the Sun is in the middle of the constellation Scorpios. In what constellation will it be in at sunset six hours later?

In Scorpius

What is the advantage of interferometry?

It allows two or more small telescopes to achieve the angular resolution of a much larger telescope

How are Earth's seasons affected by Earth's varying distance from the Sun?

It doesn't-Earth's orbital distance plays no significant role in the seasons.

The Hubble Space 2.4-meter Telescope produces such crisp images of astronomical objects because

It is above the Earths atomsphere

Why is adaptive optics useful?

It reduces blurring caused by atmospheric turbulence for telescopes on the ground.

Why is a pumpkin orange?

It reflects orange light.

Which is the most important quality of a good theory?

Its ability to make testable predictions that are later verified by new observations

This person determined that the orbits of planets are ellipses.

Kepler

Rapidly moving comets have more ___________ energy than slowly moving ones.

Kinetic

The Milky Way and Andromeda galaxies are among a few dozen galaxies that make up our ______

Local Group

What is the relation between wavelength, frequency, and energy for photons of light?

Longer wavelength means lower frequency and lower energy.

Nuclear fusion in stars converts some of the ________-energy of hydrogen nuclei into light and heat.

Mass

Our entire solar system orbits around the center of the _____________ about once every 230 million years.

Milky Way Galaxy

Electrons

Negative charge

When do solar eclipses occur?

New moon

Did Galileo detect stellar parallax?

No

Which of the following statements of the Moon is TRUE?

None of the Moon phases are caused by Earth's shadow.

Imagine a hypothetical near-Earth asteroid that has a semi-major axis (average distance from Sun) that is the same as that of the Earth. What is its period around the Sun?

One year

You are one year older each time Earth _________ about the Sun.

Orbits

According to Kepler's second law, Pluto will be traveling fastest around the Sun when at _____________

Perihelion

Kepler's 1st Law

Planets orbit on elliptical orbits with Sun at one forcus

Kepler's 2nd Law

Planets sweep out equal areas in equal time periods -> planets move faster when near Sun

This person developed a system for predicting the positions of planets that remained in use for 1,500 years.

Ptolemy

The light from Polaris travels through space in the form of __________ energy.

Radiative

Which of the following types of light could be observed from the ground?

Radio emission from a radio pulsar

The Sun appears to rise and set in our sky because Earth _______ once each day.

Rotates

The mathematical form of Kepler's third law measures the period in years and the _______________ in astronomical units (AU).

Semimajor axis

Our ___________ is moving toward the star Vega at about 70,000 km/hr.

Solar system

Kepler's 3rd Law

Square of planet's period equals the cube of the semi-major axis of orbit -> more distant planets from Sun take more time to orbit

Copernicus

Suggested a sun-centered solar system, still insisted on circular orbits, epicycles

Which of the following was not a feature of the Ptolemaic model?

The Earth orbited the sun

Why are the Moon's orbital period and rotation period the same?

The Moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period.

Suppose a planet is orbiting a star. Which is correct among the following statements for the acceleration and gravitational forces experienced by the star and the planet?

The acceleration of the planet is much more than the acceleration of the star, but the force on the star is the same but opposite the force on the planet.

If a soccer ball is kicked straight up to a height of 10 meters and then falls to the ground, which of the statements below is true about the ball's gravitational potential energy during its flight?

The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point.

In which of the situations described below is the car experiencing a net force?

The car is making a gradual turn.

If you could count all the stars in the observable universe, the number would be about the same as:

The number of grains of sand on all the beaches on Earth.

What would happen to the parallax of a star as the distance to the star from Earth increases?

The parallax shift decreases as the star's distance from Earth increases.

What kind of light(s) can be detected from a person?

The person reflects many wavelengths of visible light and emits a continuum of wavelengths of infrared light.

How did the Greeks explain retrograde motion of another planet in their geocentric model?

The planet makes small loops called epicycles as the planet orbited the Earth.

The higher the photon energy

The shorter its wavelength

What causes Earth to have seasons?

The tilt of Earth's axis causes different portions of Earth to receive more or less direct sunlight at different times of year.

Which of the following statements is true about the Sun/Earth's place in the Universe?

There is nothing particularly noteworthy about the Earth, the Sun, or the Milky Way Galaxy in terms of its size or location.

Due to its much higher density, water heated to 80 degrees (Celsius) contains more ___________ energy than air at the same temperature.

Thermal

Which travels at the higher velocity

They all travel at the same velocity

What is the fundamental difference between different elements that give them different chemical properties (for example, what makes oxygen fundamentally different from carbon)?

They have different numbers of protons in their nucleus

Ultimately, why didn't the ancient Greeks accept that the Earth went around the Sun?

They were aware of stellar parallax but were unable to measure it

True or false The Moon is constantly falling toward Earth.

True

True or false: The same element (i.e., carbon) always has the same number of protons.

True

True or false: You are currently emitting electromagnetic waves.

True

Neutrons

Uncharged

On average, galaxies are getting farther apart with time, which is why we say our _________ is expanding.

Universe

Johannes Kepler

Used ellipses rather than circles

Which of the statements below is correct regarding the energy and speed of infrared and visible light?

Visible light has higher energy, but the same speed.

In which of the following situations are you not experiencing a net force?

While you're moving upward in an elevator at a constant velocity

Which of the following statements about X-rays and radio waves is false?

X-rays travel through space faster than radio waves.

Compared to Earth, on the Moon

You would have the same mass but a different weight

If you lived on the Moon, which of the following would be true regarding your mass and weight?

Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.

You go outside and see a full moon rising at sunset. What will you see at midnight?

a full moon high in the sky

Which of the following best describes a geocentric model of the universe?

a model designed to explain what we see in the sky while having Earth located in the center of the universe

Thermal radiation laws tell us that hotter objects emit photons with _________.

a shorter average wavelength

In science, a comprehensive idea that has been tested repeatedly which gives scientists great confidence that it represents reality is called _________.

a theory

The Hubble Space Telescope is able to take crisper images of astronomical objects than most ground-based telescopes because it is:

above Earth's atmosphere.

In class, we showed that if our Solar System is shrunk by a factor of 10 billion, the Sun will be the size of a grapefruit. On this scale, how large a region would the orbits of the eight planets (out to Neptune) of the Solar System extend to?

an area a little larger than The Quad on the University of Alabama campus

Suppose you view an astronomical entity that is 2,000 light years from you. We will see it ________.

as it was 2,000 years ago

Why do astronauts on the International Space Station feel weightless?

because they and the space station are both falling around the Earth

In 240 B.C. the Greek scientist Eratothenes made a remarkably accurate estimation of the size of the Earth despite having limited resources. How did he do this?

by comparing the maximum altitude of the Sun in two cities at different latitudes

A star that is emitting a majority of its light in the infrared part of the electromagnetic spectrum is:

cooler than our Sun.

Nicholas Copernicus' most important contribution to astronomy was to _________.

create a detailed model of our solar system with the Sun rather than Earth at the center

If the distance between two objects is tripled, the gravitational law presented in class predicts that the gravitational force between the two objects _________.

decreases by a factor of 9

Radiative energy is ________.

energy carried by light

During which lunar phase is the only time a lunar eclipses can occur?

full moon

A truck is accelerating when it is

going around a circular track at a steady 100 miles per hour.

Compared to red light, blue light has higher frequency and

higher energy and shorter wavelength.

When a skater who is spinning pulls in his arms to his body, he spins faster because _________.

his angular momentum must be conserved, so reducing his radius must increase his speed of rotation

Suppose today is the new moon. When we will have the next full moon?

in about 2 weeks

Consider two objects with masses. According to the universal law of gravitation we studied in class, if you double the masses of both attracting objects, then the gravitational force between them will

increase by a factor of 4.

You and I are emitting primarily

infrared radiation.

Compared to an atom as a whole, an atomic nucleus:

is very tiny but has most of the mass.

Consider two nitrogen atoms, one containing seven neutrons and the other containing eight neutrons. These two forms of nitrogen are:

isotopes of each other.

A TV commercial stating that a piece of merchandise is light-years ahead of its time is nonsensical because _________.

it uses "light-years" to discuss time, but a light-year is a unit of distance, not time

If you are able to determine the frequency of a photon and the speed of light, what else can you determine about the photon?

its wavelength and energy

When an electron moves to a lower energy level in an atom,

light at a wavelength specific to the change in energy levels is emitted.

According to Newton's 2nd Law of Motion, the net force applied to an object equals its ________.

mass times acceleration

Momentum is defined as ________

mass times velocity

In the laboratory, you know the wavelength of a certain emission line is 656 nanometers. From the spectrum of a nebula, you see this same emission line at a wavelength of 655 nanometers. Relative to us, the star is

moving toward us

An important hydrogen absorption line occurs at a wavelength of 656.28 nanometers in the laboratory. Suppose you see that same hydrogen line in the spectrum of a star, but it has a wavelength of 656.08 nanometers. Is the star moving towards or away from us, or can we not tell?

moving towards us

Isaac Newton showed that Kepler's three laws of planetary motion are ________.

natural consequences of the law of universal gravitation

Suppose it is full moon on Earth. What phase of Earth would an observer on the Moon see at this time?

new Earth

Tycho Brahe's most important contribution to astronomy was to _________.

observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion

The Earth completes one revolution around the Sun every ________.

one year

If the distance from the Earth to the Sun were doubled its current distance, the force of gravity between Earth and the Sun would be

one-quarter as strong as the current force.

How old is our Solar System compared to the age of the Universe?

one-third of the age of the universe.

A spectral line that appears at a wavelength of 321 nanometers in the laboratory appears at a wavelength of 328 nanometers in the spectrum of a distant object. We say that the object's spectrum is:

redshifted.

Which of the following is largest?

size of a typical galaxy

Galileo observed all of the following EXCEPT ___________

stellar parallax

Galileo

sun centered model

We always see the same side of the Moon from Earth because

the Moon's rotation period is the same as its orbital period.

Our Solar System is composed of _________.

the Sun and all the objects that orbit it

The wavelength of a wave is

the distance between two adjacent peaks of the wave.

Suppose Earth's orbit was changed such that it took twice as long to orbit the Sun than it does now, but its axis tilt and rotation period were the same as now. In this situation ________.

the four seasons would each be twice as long as they are now

Suppose you look at an astronomical image of a region of the sky containing a number of galaxies at various distances from us. If you assume that the galaxies in the image formed more or less at the same time following the Big Bang, which galaxy would appear to be the youngest to us?

the galaxy that is furthest from us

In Einstein's formula E = mc2, what does E represent?

the mass-energy, or potential energy stored in an object's mass

What is the ecliptic?

the path the Sun appears to trace around the celestial sphere each year

A planet's angular momentum when it is nearest to the Sun is ____________ its angular momentum when it is farthest from the Sun

the same as

How large is the observable Universe (if the Milky Way Galaxy is the size of a football field)?

the size of the Pacific Ocean

Which of the following is the best description of the Universe?

the sum total of all matter and energy

If two objects collide with one another, which of the following quantities is NOT necessarily the same both before and after the collision event?

the total temperature of the objects

Which piece of information is most useful to determine the chemical composition of a star?

the wavelengths of spectral lines in the star's spectrum

In the Earth-centered model of Ptolemy other planets orbited Earth on "circles upon circles", or epicycles. Why was this a necessary feature of the model?

to explain the fact that planets sometimes appear to move westward, rather than eastward, relative to the stars in our sky

Stars in the night sky twinkle because of _________.

turbulence in Earth's atmosphere

The difference between speed and velocity is that ________.

velocity also includes a direction

Consider two far away galaxies, Galaxy A and Galaxy B. If Galaxy A is half as distant as Galaxy B then ________.

we are seeing Galaxy A as it looked at a later time in the history of the universe than Galaxy B

Many comets have highly elliptical orbits around the Sun. Where in its orbit around the Sun is a comet moving the fastest?

when it is closest to the Sun

In which of the situations below would you feel weightless?

while falling from a roof