AY 101 HW 2

Which of the following statements expresses what we mean by a scientific theory? -an educated guess -an explanation for a physical phenomenon, an explanation that hasn't been tested yet -a simple model that explains a wide variety of phenomena and that has survived repeated tests -an hypothesis

a simple model that explains a wide variety of phenomena and that has survived repeated tests

In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called _________. -a Ptolemaic model -a paradigm -a theory -a hypothesis

a theory

Scientific thinking is _________. -a difficult process that only a handful of people can do well -based on everyday ideas of observation and trial-and-error experiments -an ancient mode of thinking first invented in Egypt -completely different from any other type of thinking

based on everyday ideas of observation and trial-and-error experiments

Why are astronauts weightless in the Space Station? because the Space Station is moving at constant velocity because they are in a vacuum and floating in their spacesuits because the Space Station is constantly in free-fall around the Earth because there is no gravity so far from Earth

because the Space Station is constantly in free-fall around the Earth

At which lunar phase(s) are tides least pronounced (e.g., the lowest high tides)? new moon full moon first quarter both new and full moons both first and third quarters

both first and third quarters

From Kepler's third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to -8 astronomical units. -2 astronomical units. -16 astronomical units. -4 astronomical units. -It depends on the asteroid's mass.

4 astronomical units.

If your mass is 60 kg on Earth, what would your mass be on the Moon? 60 kg 50 kg 10 lb 10 kg 60 lb

60 kg

Which of the following scenarios involves energy that we would typically calculate with Einstein's formula E = mc2? A small amount of the hydrogen in a nuclear bomb (an H-bomb) becomes energy as fusion converts the hydrogen to helium. A mass raised to a great height has a lot of gravitational potential energy. An object accelerated to a great speed has a lot of kinetic energy. A burning piece of wood produces light and heat, therefore giving off radiative and thermal energy.

A small amount of the hydrogen in a nuclear bomb (an H-bomb) becomes energy as fusion converts the hydrogen to helium.

Kepler's third law, p^2 = a^3, means that -all orbits with the same semi-major axis have the same period. -a planet's period does not depend on the eccentricity of its orbit. the period of a planet does not depend on its mass. -planets that are farther from the Sun move at slower average speeds than nearer planets. -All of the above are correct.

All of the above are correct.

What is the difference between a bound orbit and an unbound orbit around the Sun? An object on a bound orbit follows the same path around the Sun over and over, while an object on an unbound orbit approaches the Sun just once and then never returns. An object on a bound orbit has a gravitational attraction to the Sun, while an object on an unbound orbit does not. A bound orbit is circular, while an unbound orbit is elliptical. A bound orbit is an orbit allowed by the universal law of gravitation, and an unbound orbit is not.

An object on a bound orbit follows the same path around the Sun over and over, while an object on an unbound orbit approaches the Sun just once and then never returns.

How does a rocket launch upwards? Choose the statement that best describes why a rocket goes up. By expelling gas downwards, the rocket is propelled upwards. By expelling gas downwards, which pushes against the ground, the rocket is propelled upwards. By expelling gas, the rocket loses mass; because it is lighter, it rises up.

By expelling gas downwards, the rocket is propelled upwards.

When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not? -Copernicus placed the planets in the wrong order going outward from the Sun. -Copernicus used perfect circles for the orbits of the planets. -Copernicus misjudged the distances between the planets. -Copernicus placed the Sun at the center but did not realize that the Moon orbits the Earth.

Copernicus used perfect circles for the orbits of the planets.

Suppose that the Sun shrank in size but that its mass remained the same. What would happen to the orbit of the Earth? Earth's orbit would expand, and it would take more than one year to orbit the Sun. The size of Earth's orbit would shrink, and it would take less than one year to orbit the Sun. Earth would change from a bound orbit to an unbound orbit and fly off into interstellar space. Earth's orbit would be unaffected.

Earth's orbit would be unaffected.

There is no gravity in space. True False

False

Where does the energy come from that your body uses to keep you alive? It is produced from the radiative energy of the Sun on your skin. It is in the air that you breathe. It comes from the foods you eat. It is created during the time that you rest or sleep. It comes from the water you drink.

It comes from the foods you eat.

If a spinning star suddenly gets bigger in diameter, what happens to its rotation rate? It is unaffected. It decreases. It increases.

It decreases.

What practical value did astronomy offer to ancient civilizations? -It helped them understand our cosmic origins. -It helped them find uses for ancient structures like Stonehenge. -It allowed them to predict eclipses with great accuracy. -It helped them keep track of time and seasons, and it was used by some cultures for navigation.

It helped them keep track of time and seasons, and it was used by some cultures for navigation.

Which statement must be true in order for a rocket to travel from Earth to another planet? It must attain escape velocity from Earth. It must carry a lot of extra fuel. It must have very large engines. It must be launched from space, rather than from the ground.

It must attain escape velocity from Earth.

Why is a sunflower yellow? It emits yellow light. It absorbs yellow light. It reflects yellow light.

It reflects yellow light.

What do astronomers mean by light pollution? Light pollution means contamination of light caused by chemicals in the Earth's atmosphere. Light pollution is a type of air pollution created by lightweight gases such as hydrogen and helium. Light pollution is light from human sources that makes it difficult to see the stars at night. Light pollution is a term used to describe the appearance of the sky in regions that are crowded with stars.

Light pollution is light from human sources that makes it difficult to see the stars at night.

How are wavelength, frequency, and energy related for photons of light? Longer wavelength means higher frequency and higher energy. Longer wavelength means higher frequency and lower energy. Longer wavelength means lower frequency and lower energy. Longer wavelength means lower frequency and higher energy. There is no simple relationship because different photons travel at different speeds

Longer wavelength means lower frequency and lower energy.

Which of the following is not true about scientific progress? -Science progresses through the creation and testing of models of nature. -Science advances only through the scientific method. -Science avoids explanations that invoke the supernatural.

Science advances only through the scientific method.

Which of the following statements best describes the two principal advantages of telescopes over eyes? Telescopes can collect far more light with far greater magnification. Telescopes can collect far more light with far better angular resolution. Telescopes have much more magnification and better angular resolution. Telescopes collect more light and are unaffected by twinkling.

Telescopes can collect far more light with far better angular resolution.

Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight? The ball's gravitational potential energy is always the same. The ball's gravitational potential energy is greatest at the instant the ball leaves your foot. The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point. The ball's gravitational potential energy is greatest at the instant it returns to hit the ground.

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

Which of the following is not one of, nor a direct consequence of, Kepler's Laws? -More distant planets orbit the Sun at slower speeds. -The force of attraction between any two objects decreases with the square of the distance between their centers. -The orbit of each planet about the Sun is an ellipse with the Sun at one focus. -As a planet moves around its orbit, it sweeps out equal areas in equal times.

The force of attraction between any two objects decreases with the square of the distance between their centers.

In the Greek geocentric model, the retrograde motion of a planet occurs when: -Earth is about to pass the planet in its orbit around the Sun. -The planet actually goes backward in its orbit around Earth. -The planet is aligned with the Moon in our sky.

The planet actually goes backward in its orbit around Earth.

Imagine a spaceship in orbit around a planet. Its engine suffers a severe malfunction and explodes. What is the most physically realistic depiction of this event? The spacecraft breaks apart, and the pieces continue to orbit the planet. The spacecraft breaks in half and begins to sink down into the planet, like a sinking aircraft carrier. The spacecraft burns up in a giant fireball.

The spacecraft breaks apart, and the pieces continue to orbit the planet.

Suppose a star is moving toward us at a high velocity. The wavelength of its spectral lines would be shorter and their frequencies would be lower. The wavelengths of its spectral lines would be shorter but their frequencies would be the same. The wavelengths of its spectral lines would be shorter and their frequencies would be higher. Its light would arrive to us at a higher velocity than if the star were stationary.

The wavelengths of its spectral lines would be shorter and their frequencies would be higher.

Suppose you drop a feather and a hammer on the Moon from the same height at the same time. What will happen? The feather will hit the ground first. They will float in space because of the lack of gravity on the Moon. The hammer will hit the ground first. They will hit the ground at the same time.

They will hit the ground at the same time.

The Chandra X-ray Observatory must operate in space because X-ray telescopes require the use of grazing incidence mirrors. X-rays are too dangerous to be allowed on the ground. It was built by NASA. X-rays do not penetrate Earth's atmosphere.

X-rays do not penetrate Earth's atmosphere.

Which of the following statements about X-rays and radio waves is not true? X-rays and radio waves are both forms of light, or electromagnetic radiation. X-rays travel through space faster than radio waves. X-rays have higher frequency than radio waves. X-rays have shorter wavelengths than radio waves.

X-rays travel through space faster than radio waves.

What do we mean by a geocentric model of the universe? -a model designed to explain what we see in the sky while having Earth orbit the Sun -a model designed to explain what we see in the sky while having Earth located in the center of the universe -the name given to sphere-shaped models that show all the constellations as they appear in our sky on the celestial sphere -a model of the Milky Way Galaxy that has our solar system located at its center

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

Which of the following represents a case in which you are not accelerating? -driving in a straight line at 60 miles per hour -slamming on the brakes to come to a stop at a stop sign -going from 0 to 60 miles per hour in 10 seconds -driving 60 miles per hour around a curve

driving in a straight line at 60 miles per hour

How much greater is the light-collecting area of a 6-meter telescope than a 3-meter telescope? two times four times six times

four times

As an interstellar cloud of hydrogen gas shrinks in size, its rate of rotation increases, because its total energy is conserved. decreases, because the force of gravity strengthens as the cloud shrinks. increases, because the force of gravity strengthens as the cloud shrinks. increases, because its angular momentum is conserved. decreases, because its angular momentum is conserved.

increases, because its angular momentum is conserved.

When an electron drops to a lower energy level in an atom, light at a wavelength specific to the change in energy levels is emitted. the extra energy disappears. the atom moves more slowly. the electron becomes more massive.

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

Red light has a lower energy per photon than blue light. Therefore, red light has higher frequency, shorter wavelength than blue light. lower frequency, shorter wavelength than blue light. lower frequency, longer wavelength than blue light. higher frequency, longer wavelength than blue light.

lower frequency, longer wavelength than blue light.

Galileo's contribution to astronomy included: -discovering the laws of planetary motion. -discovering the law of gravity. -making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

Galileo challenged the idea that objects in the heavens were perfect by ________. -showing that heavy objects fall at the same rate as lighter objects -observing sunspots on the Sun and mountains on the Moon -inventing the telescope -proving Kepler's laws were correct

observing sunspots on the Sun and mountains on the Moon

Thermal radiation is defined as _________. radiation produced by an extremely hot object radiation with a spectrum whose shape depends only on the temperature of the emitting object radiation that is felt as heat radiation in the form of emission lines from an object

radiation with a spectrum whose shape depends only on the temperature of the emitting object

Which of the following observational techniques is appropriate for measuring Doppler shifts? timing (measuring how the amount of light changes with time) imaging (taking a picture) spectroscopy (taking a spectrum)

spectroscopy (taking a spectrum)

Which is an essential quality of an accepted scientific result? -support by many scientists -agreement with previous models -mathematical elegance -testability

testability

One star is emitting primarily visible light and another star is emitting primarily infrared light. Which star is hotter? the star emitting visible light the star emitting infrared light Both stars are the same temperature. The temperature also depends on the radius of the star, so one can't decide based on the information provided.

the star emitting visible light

Cell phone signals passing through walls is an example of transmission. reflection or scattering. emission. absorption.

transmission.

Scientific theories can never be proved true beyond all doubt. True False

true

The energy levels for electrons vary from one element to another. True False

true

The stars in our sky twinkle in brightness and color because of _________. turbulence in Earth's atmosphere light pollution the bubbling and boiling of gases on the surfaces of stars rapid changes in the brightnesses and colors of stars caused by changes in their spectra

turbulence in Earth's atmosphere

The difference between speed and velocity is that ________. -velocity also includes a direction -velocity is calculated using a physics equation -they are expressed in different units -velocity is the same as acceleration but speed is different

velocity also includes a direction

When is a comet's orbital speed at its maximum? when it is farthest from the Sun when it is closest to the Sun Its orbital speed does not change.

when it is closest to the Sun