Astronomy Ch 4-5

Currently, the largest optical telescope mirrors have a diameter of

10 m

The acceleration of gravity on Earth is approximately 10 m/s2 (more precisely, 9.8 m/s2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds?

30 m/s

Which of the following statements about thermal radiation is always true?

A hot object emits more radiation per unit surface area than a cool object.

Which of the following statements about electrical charge is true?

A positive charge and a negative charge will attract each other.

Which of the following statements about X rays and radio waves is not true?

X rays travel through space faster than radio waves.

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons

We can see each other in the classroom right now because we

reflect visible light

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes? It is closer to the stars. Stars do not twinkle when observed from space. It can observe infrared and ultraviolet light, as well as visible light. It never has to close because of cloudy skies.

It is closer to the stars.

Which of the following statements is true of green grass?

It absorbs red light and reflects green light.

is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color? It is moving away from us. It is much brighter than the Sun. Its surface is cooler than the surface of the Sun. It is much more massive than the Sun.

Its surface is cooler than the surface of the Sun.

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Star X is moving away from us faster than Star Y.

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

The cloud is cool and lies between you and a hot star.

Which of the following best describes why we say that light is an electromagnetic wave?

The passage of a light wave can cause electrically charged particles to move up and down.

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?

The photo will seem to show only one star rather than two.

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true? The peak of the star's thermal emission tells us its temperature: hotter stars peak at shorter (bluer) wavelengths. Shifts in the wavelengths of spectral lines compared to the wavelengths of those same lines measured in a laboratory on Earth can tell us the star's speed toward or away from us. We can identify chemical elements present in the star by recognizing patterns of spectral lines that correspond to particular chemicals. The total amount of light in the spectrum tells us the star's radius.

The total amount of light in the spectrum tells us the star's radius.

Which of the following is always true about images captured with X-ray telescopes?

They are always shown with colors that are not the true colors of the objects that were photographed.

Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?

They have a frequency of 2 hertz.

The Chandra X-ray Observatory must operate in space because:

X rays do not penetrate Earth's atmosphere.

Radio waves are:

a form of light

According to the laws of thermal radiation, hotter objects emit photons with _________.

a shorter average wavelength

Which of the following wavelength regions cannot be studied with telescopes on the ground? radio waves ultraviolet x rays both B and C both A and C

both b and c

Consider the statement "There's no gravity in space." This statement is:

false

To make a rocket turn left, you need to:

fire an engine that shoots out gas to the right.

A car is accelerating when it is

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

The spectra of most galaxies show redshifts. This means that their spectral lines _________.

have wavelengths that are longer than normal

Compared to red light, blue light has higher frequency and

higher energy and shorter wavelength

If the Moon were closer to Earth, high tides would

higher than they are now

When an atom loses an electron, it becomes

ionized

Compared to an atom as a whole, an atomic nucleus

is very tiny but has most of the mass.

Some nitrogen atoms have seven neutrons and some have eight neutrons. These two forms of nitrogen are:

isotopes of each other

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?

its wavelength and energy

Compared to their values on Earth, on another planet your

mass would be the same but your weight would be different.

A planet with twice Earth's mass orbiting at a distance of 1 AU from a star with the same mass as the Sun.

one year

In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?

radio

From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?

radio, infrared, visible light, ultraviolet, X rays, gamma rays

A planet with the same mass as Earth orbiting at a distance of 1 AU from a star with four times the Sun's mass.

six months

The wavelength of a wave is

the distance between two adjacent peaks of the wave.

Compared to its angular momentum when it is farthest from the Sun, Earth's angular momentum when it is nearest to the Sun is

the same

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

the star is moving toward us

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

the wavelengths of spectral lines in the star's spectrum