AST 105 Review for Exam #2 Fall 2003
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) The allowed shapes for orbits under the force of gravity are
A) ellipses only.
B) ellipses and spirals.
C) ellipses, parabolas, and hyperbolas.
D) ellipses, spirals, and parabolas.
E) spirals, circles, and squares.
2) Thermal radiation is defined as
A) radiation produced by a hot object.
B) radiation in the infrared part of the spectrum.
C) radiation that depends only on the emitting object's temperature.
D) radiation in the form of emission lines from an object.
E) radiation that is felt as heat.
3) You observe a distant galaxy. You find that a spectral line normally found in the visible
part of the spectrum is shifted toward the infrared. What do you conclude?
A) The galaxy is moving away from you.
B) The galaxy is moving toward you.
C) The galaxy has very weak gravity.
D) The galaxy is made purely of hydrogen.
E) The composition of the galaxy is changing.
4) Newton's second law of motion tells us that the net force applied to an object equals its
A) mass times energy.
B) momentum times velocity.
C) mass times velocity.
D) energy times acceleration.
E) mass times acceleration.
5) Which of the following could not be determined by an observation that uses only
spectroscopy?
A) the chemical composition of a distant star
B) the speed at which a distant galaxy is moving away from us
C) the surface temperature of a distant star
D) the rotation rate of a distant star
E) the size of a distant galaxy
6) Without telescopes or other aid, we can look up and see the Moon in the night sky because it
A) emits visible light.
B) emits thermal radiation.
C) reflects infrared light.
D) reflects visible light.
E) glows through radioactive decay.
7) When an electron in an atom goes from a higher energy state to a lower energy state, the
atom
A) emits a photon of a specific frequency.
B) absorbs a photon of a specific frequency.
C) absorbs several photons of a specific frequency.
D) can emit a photon of any frequency.
E) can absorb a photon of any frequency.
8) You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude?
A) The elevator is accelerating upwards.
B) The elevator is moving at a constant velocity upwards.
C) The elevator is accelerating downwards.
D) The elevator is moving at a constant velocity downwards.
E) Your diet is working.
9) Which of the following is an example in which you are traveling at constant speed but not at constant velocity?
A) rolling freely down a hill in a cart, traveling in a straight line
B) driving backward at exactly 50 km/hr
C) driving around in a circle at exactly 100 km/hr
D) jumping up and down, with a period of exactly 60 hops per minute
E) none of the above
10) Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
A) The red star is more massive than the blue star.
B) The blue star is more massive than the red star.
C) The blue star is farther away than the red star.
D) The blue star has a hotter surface temperature than the red star.
E) The red star has a hotter surface temperature than the blue star.
11) What quantities does angular momentum depend upon?
A) mass and velocity
B) mass, velocity, and radius
C) force and radius
D) force, velocity, and radius
E) momentum and angular velocity
12) How are wavelength, frequency, and energy related for photons of light?
A) Longer wavelength means lower frequency and lower energy.
B) Longer wavelength means higher frequency and lower energy.
C) Longer wavelength means higher frequency and higher energy.
D) Longer wavelength means lower frequency and higher energy.
E) There is no simple relationship because different photons travel at different speeds.
13) When an atom absorbs a photon containing energy, any of the following can happen
except which?
A) The atom becomes excited.
B) The atom is ionized.
C) An electron moves from an upper energy level to a lower one.
D) An electron moves from a lower energy level to an upper one.
14) From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?
A) infrared, visible light, ultraviolet, X rays, gamma rays, radio
B) radio, infrared, visible light, ultraviolet, X rays, gamma rays
C) visible light, infrared, X rays, ultraviolet, gamma rays, radio
D) gamma rays, X rays, ultraviolet, visible light, infrared, radio
E) gamma rays, X rays, visible light, ultraviolet, infrared, radio
15) When an atom loses an electron, it becomes
A) sublimated.
B) dissociated.
C) ionized.
D) an isotope.
E) a plasma.
16) Suppose an object is moving in a straight line at 50 mi/hr. According to Newton's first law of motion, the object will
A) continue to move in the same way forever, no matter what happens.
B) continue to move in the same way until it is acted upon by a force.
C) eventually slow down and come to a stop.
D) continue to move in a straight line forever if it is in space, but fall to the ground if it is on
Earth.
17) Which of the following statements about X rays and radio waves is not true?
A) Neither X rays nor radio waves can penetrate the Earth's atmosphere.
B) X rays have shorter wavelengths than radio waves.
C) X rays and radio waves are both forms of light, or electromagnetic radiation.
D) X rays have higher frequency than radio waves.
E) X rays have higher energy than radio waves.
18) The spectra of most galaxies show redshifts. This means that their spectral lines
A) always are in the red part of the visible spectrum.
B) have wavelengths that are longer than normal.
C) have wavelengths that are shorter than normal.
D) have a higher intensity in the red part of the spectrum.
E) have normal wavelengths, but absorption of light makes them appear red.
19) How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
A) It loses kinetic energy.
B) It releases a photon equal in energy to its own energy drop.
C) It absorbs a photon equal in energy to its own energy drop.
D) It loses gravitational potential energy.
E) It exchanges gravitational potential energy for kinetic energy.
20) If your mass is 60 kg on Earth, what would your mass be on the Moon?
A) 10 lb B) 10 kg C) 50 kg D) 60 kg E) 60 lb
21) Momentum is defined as
A) mass times speed.
B) mass times velocity.
C) force times velocity.
D) mass times acceleration.
E) force times acceleration.
22) According to the universal law of gravitation, the force due to gravity is
A) directly proportional to the square of the distance between objects.
B) inversely proportional to the square of the distance between objects.
C) directly proportional to the distance between objects.
D) inversely proportional to the distance between objects.
E) not dependent on the distance between objects.
23) Grass (that is healthy) looks green because
A) it emits green light and absorbs other colors.
B) it absorbs green light and emits other colors.
C) it transmits green light and emits other colors.
D) it reflects green light and absorbs other colors.
24) From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude?
A) The star is moving toward us.
B) The star is moving away from us.
C) The star is getting hotter.
D) The star is getting colder.
E) The "star" actually is a planet.
25) The frequency of a wave is
A) the number of peaks passing by any point each second.
B) measured in cycles per second.
C) measured in hertz (Hz).
D) equal to the speed of the wave divided by the wavelength of the wave.
E) all of the above.
1) Answer: C
2) Answer: C
3) Answer: A
4) Answer: E
5) Answer: E
6) Answer: D
7) Answer: A
8) Answer: C
9) Answer: C
10) Answer: D
11) Answer: B
12) Answer: A
13) Answer: C
14) Answer: D
15) Answer: C
16) Answer: B
17) Answer: A
18) Answer: B
19) Answer: B
20) Answer: D
21) Answer: B
22) Answer: B
23) Answer: D
24) Answer: A
25) Answer: E
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