Exam #1 Review

Astronomy 103, Spring ‘09Timbie/Schechtman-Rook

If a beam of light has awavelength of 10-6 meters,

what is its frequency?• A. 3x102 Hz.• B. 3x1014 Hz.• C. 3x10-14 Hz.• D. 3x108 Hz.

You are standing at a latitude25o north of the equator. Whatangle does the Sun make withthe southern horizon at noon

on the Summer solstice?• A. 50o.• B. 1.5o.• C. 48.5o.• D. None of the above.

Which kind of photon has thehighest energy?

• A. Radio.• B. Visible.• C. Infrared.• D. X-ray.

The temperature of ablackbody with λmax = 1 cm is:

• A. 0.29 K• B. 5800 K• C. 3 K• D. 0.05 K

An asteroid orbits the Sun at adistance of 2 AU. What is its

period?• A. 1.4 years.• B. 2.8 years.• C. 4.0 years.• D. 8.0 years.

Name all three of Kepler’slaws:

Name two of Newton’s Lawsof motion:

Galileo used his observationsof the changing phases ofVenus to demonstrate that

• A. the Sun moves around the Earth.• B. the Earth is a sphere.• C. the Moon orbits the Earth.• D. Venus follows an orbit around the

Sun rather than the Earth.

If we measure that a certainemission line is blue-shiftedon one side of a galaxy and

red-shifted on the other, whatdo we conclude?

• A. The galaxy is moving towards us.• B. The galaxy is moving away from us.• C. The galaxy is merging.• D. The galaxy is rotating.

A sidereal day is

• A. the time it takes for a star directlyoverhead to return to being directlyoverhead.

• B. Measured using the Sun.• C. Dependent on your latitude.• D. B & C.

Which of the following is NOTequivalent to 30 kilometers?

• A. 30,000 meters.• B. 3x106 centimeters.• C. 3x103 meters.• D. 30,000,000 millimeters.

If an object moves along acurved path at a constantspeed, you can infer that

• A. a force is acting on it.• B. it is losing mass.• C. it is accelerating.• D. both A & C.

Two spaceships having differentmasses but rocket engines of

identical force coast together throughspace at constant velocity. If they firetheir rockets at the same time, whichof the two ships will speed up faster?• A. The one with the lower mass.• B. The one with the higher mass.• C. They will speed up equally, because they

have identical rocket engines.• D. They cannot speed up at all, because they

are in space.

If you double the distancebetween two objects, anddouble the masses of bothobjects, the force of gravity

between the two• A. Decreases by a factor of two.• B. Increases by a factor of two.• C. Stays the same.• D. None of the above.

A neon sign emits a bright redglow because

• A. the strongest neon emission lines in the visiblepart of the spectrum are around 400 nm.

• B. the strongest neon emission lines in the visiblepart of the spectrum are around 700 nm.

• C. it is a blackbody with a peak wavelength around400 nm.

• D. it is a blackbody with a peak wavelength around700 nm.

If an object’s temperaturedoubles, its total flux

• A. increases by a factor of two.• B. decreases by a factor of two.• C. increases by a factor of 16.• D. increases by a factor of four.

If the wavelength of a photondoubles, its energy

• A. is halved.• B. doubles.• C. remains the same.• D. is quartered.

An object in orbit around theEarth stays in orbit because

• A. the spin of the Earth propels itoutward.

• B. gravity is much weaker in space.• C. the gravity of the other planets

balances out the Earth’s gravity.• D. none of the above.

When a photon interacts withan atom, what changes occur

in the atom?• A. The atomic number increases.• B. The nucleus begins to glow.• C. An electron changes its orbital.• D. The photon becomes trapped in

orbit.

If the Sun’s declination is 0o onMarch 21 of a particular year,how long will it be before it is

at this declination again?• A. 1 year.• B. 6 months.• C. 26,000 years.• D. Always - the declination of the Sun is

0o by definition.

The most famous personassociated with the

heliocentric model is:• A. Aristotle.• B. Nicolaus Copernicus.• C. Leonardo Da Vinci.• D. Tycho Brahe.

3.14x10-1 + 6.86x104 is mostclosely approximated by:

• A. 10x104

• B. 3.72x104

• C. 7.17x104

• D. 6.86x104

If a [=] kg/(m*s) and b [=]W*m2, a*b [=]

• A. W*kg/s.• B. W*m*kg/s.• C. Newtons.• D. W*kg/(m*s)

In New York City, theconstellation Orion is high in

the sky around 11 pm inJanuary. At what time of theday or night would Orion be

high in the sky in July?• A. 5 AM.• B. 11 AM.• C. 5 PM.• D. 11 PM.

Retrograde motion is:

• A. The apparent backwards motion ofthe planets against the stars.

• B. Due to the orbits of the Earth and theplanets around the Sun.

• C. Explained by epicycles in thePtolemiac model.

• D. All of the above.

The seasons are caused by

• A. the Earth being much closer to the Sunin the summer, and much further in thewinter.

• B. The tilt of the Earth increases theamount of sunlight the Earth receives inthe summer.

• C. The Sun changes emits more light inthe summer than in the winter.

• D. None of the above.

Increasing the temperature ofa star _________ the peakwavelength of its spectrum.

• A. increases• B. cancels out• C. decreases• D. does not change