Ch. 3, and 4 Notes, reading quizzes, and homework

A net force must be acting on: a. A car coming to a stop b. An elevator moving up at constant speed c. A moon orbiting Jupiter d. All of the above e. a and c only

e

What is speed?

the rate at which an object position changes

What is Kepler's third law?

3. More distant planets orbit the Sun at slower average speeds: p2 = a3. p= orbital period in years a= average distance from the sun in AU

What is its average distance (semimajor axis) from the Sun?

67.7 AU

The shadow cast by a simple stick or obelisk allowed ancient people to a. tell the time of day b. observe retrograde motion of the planets c. show that the solar system is really Sun-centered d. record accurate measurements of the motions of the stars

a. tell the time of day

How is modern science rooted in ancient astronomy?

-Astronomy is the oldest of the sciences. - it was often practiced for practical reasons. a. kept track of time and seasons b. for religious and ceremonial purposes - aiding navigation

Newton's Third Law

-For every force, there is an equal and opposite reaction force - Forces are interactions between objects, momentum can be transferred from one to another

Acceleration of Gravity (g)

-Galileo showed that g is the same for all falling objects, regardless of their mass. - Apollo 15 demonstrated air resistance on Earth means different objects can fall at different times

escape velocity

-If an object gains enough orbital energy, it may escape (change from a bound to unbound orbit). -Escape velocity from Earth ≈ 11 km/s from sea level (about 40,000 km/hr).

gravitational potential energy

-In space, an object or gas cloud has more gravitational energy when it is spread out than when it contracts. -A contracting cloud converts gravitational potential energy to thermal energy.

How does gravity cause tides?

-Moon's gravity pulls harder on near side of Earth than on far side. -Difference in Moon's gravitational pull stretches Earth.

Newton generalized kepler's third law how?

-Newton's version of Kepler's third law: If a small object orbits a larger one and you measure the orbiting object's orbital period AND average orbital distance THEN you can calculate the mass of the larger object.

What is the Ptolemaic model?

-Sufficiently accurate to remain in use for over 1500 years. - Arabic translation of Ptolemy's work name Almagest ("the greatest compilation")

conservation of angular momentum

-The total angular momentum of a system cannot change unless an external force (torque) is acting on them. - External =from environment - Interacting objects within the system can exchange angular momentum

tidal friction

-Tidal friction gradually slows Earth's rotation (and makes the Moon get farther from Earth). - Moon once orbited faster (or slower); tidal friction caused it to "lock" in synchronous rotation.

How do gravity and energy together allow us to understand orbits?

-Total orbital energy (gravitational + kinetic) stays constant if there is no external force. -Orbits cannot change spontaneously.

Radiative Energy

-energy carried by electromagnetic waves, or light - When you stand outside on a nice day, you absorb radiative energy from the sun

Hallmarks of Science #2

Science progresses through the creation and testing of models of nature that explain the observations as simply as possible *Simplicity= "Occam's razor"

In what ways do all humans employ scientific thinking?

Scientific thinking is based on everyday ideas of observation and trial-and-error experiments.

Acceleration of Gravity near Earth's Surface

-All falling objects accelerate at the same rate (ignoring air resistance). - On Earth g ≈ 10 m/s2: speed increases 10 m/s with each second falling.

What did ancient civilizations achieve in astronomy?

-Daily timekeeping - tracking the seasons and calendar -monitoring lunar cycles -monitoring planets and stars -predicting eclipses

What happened in 1633?

The Catholic Church ordered Galileo to recant his claim that Earth orbits the Sun.

What determines the strength of gravity?

The Universal law of Gravitation: a. Every mass attracts every other mass. b. Attraction is directly proportional to the product of their masses. c. Attraction is inversely proportional to the square of the distance between their centers.

An asteroid with an average orbital distance of 2 AUAU will orbit the Sun at an average speed that is __________. a. a little slower than the orbital speed of Mars b. a little faster than the orbital speed of Mars c. the same as the orbital speed of Mars

a

All of the following statements are true. Which one can be explained by Kepler's second law? a. The Sun is not in the precise center of Saturn's orbit. b. All the planets orbit the Sun in nearly the same plane. c. Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun. d. Venus orbits the Sun at a faster orbital speed than Earth. e. Earth is slightly closer to the Sun in January than in July.

c. Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun.

True or false: The days of the week were named for the Sun,Moon, and visible planets?

True

True or false: Thermal energy is a measure of the total kinetic energy of all the particles in a substance. It therefore depends on both temperature AND density

True

True or false: could the ancient people of central Africa(6500 B.C.) predict season from the orientation of the crescent moon?

True

Overcoming the second objection (heavenly perfection):

Tycho's observations of comet and supernova already challenged this idea. -Using his telescope, Galileo saw: -Sunspots on the Sun ("imperfections") - Mountains and valleys on the Moon (proving it is not a perfect sphere)

conserved quantity

Unchanging in time. A quantity is "conserved" if the amount of that quantity does not change in time, even though processes may be changing its form. - Closed (or isolated): no interaction with environment

Thought Question On the Moon, a. your weight is the same; your mass is less. b. your weight is less; your mass is the same. c. your weight is more; your mass is the same. d. your weight is more; your mass is less

b

How can motion be measured?

position can be measured in meters, feet, kilometers, AU, lightyear, miles Time can be meausred in seconds, years, hours

What is the idealized scientific method?

- Based on proposing and testing hypotheses. - Hypothesis= educated guess

Where do object get their energy?

- Energy makes matter move - Energy is conserved, but it can: a. transfer from one object to another. - change in form

True or False: Concentrated energy can spontaneously turn into particles

True

Newton's Second Law

Force = mass x acceleration -If there is a net force, there is an acceleration - If there is an acceleration, there is a net force -For the same force, smaller masses have a larger acceleration than larger masses

Thermal energy

- The collective kinetic energy of many particles (for example, in a rock, in air, in water) - Thermal energy is related to temperature but it is NOT the same. Temperature is the average kinetic energy of the many particles in a substance.

Overcoming the third objection (parallax):

- Tycho thought he had measured stellar distances, so lack of parallax seemed to rule out an orbiting Earth. - Galileo showed stars must be much farther than Tycho thought — in part by using his telescope to see the Milky Way is countless individual stars. - If stars were much farther away, then lack of detectable parallax was no longer so troubling.

What were the three philosophical innovations?

- Understand nature without relying on supernatural explanations - use math to give precision to ideas - use observations of nature

potential energy

- Energy that is stored and can be retrieved later - Putting a jar on a shelf takes energy, later if it falls, that energy is reclaimed (it is transformed into kinetic energy) a. Gravitational potential energy b. Chemical potential energy c. Electrical potential energy d. Elastic potential energy e. Mass-Energy

How did Kepler challenge the Earth-centered idea?

- First tried to match Tycho's observations with circular orbits. - doing this led him to an 8-arcminute discrepancy which then led to ellipses

Overcoming the first objection (nature of motion):

- Galileo's experiments showed that objects in air would stay with Earth as it moves. - Aristotle thought that all objects naturally come to rest. - Galileo showed that objects will stay in motion unless a force acts to slow them down (Newton's first law of motion).

How did Tycho challenge the Earth-centered idea?

- He compiled the most accurate (1 arcminute) naked eye measurements ever made of planetary positions. - HE still couldn't detect the stellar parallax causing him to think the Earth must be the center of the solar system. *he did recognize that the other planets did go around the sun* - He hired Kepler, who used Tycho's observations to discover the truth about planetary motion.

How did Newton change our view of the universe?

- He realized the same physical laws that operate on Earth also operate in the heavens, -Discovered laws of motion and gravity - Experiments with light; first reflecting telescope, calculus

How does Newton's law of gravity extend Kepler's laws?

- Kepler's first two laws apply to all orbiting objects, not just planets. - Ellipses are not the only orbital paths. Orbits can be: a. bound (ellipses) b. unbound 1. parabola 2. hyperbola

What is absolute zero?

0 K, -273.15 C, -459.67 degrees F

At what temperature does water freeze?

0 degrees Celsius and 32 degrees Fahrenheit, 273.15 K

What are Kepler's first law of planetary motion?

1. The orbit of each planet around the sun is an ellipse with the Sun at one focus.

How far does the planet in part F orbit from the Sun?

10 AU

At what temperature does water boil?

100 degrees Celsius and 212 degrees Fahrenheit, 373.15 K

Jupiter orbits the Sun at an average distance of 5.203AU and takes 11.86 years to complete each orbit. Based on these facts, which statement is true?

11.86^2= 5.203^3 Kepler's third law can be stated mathematically as p2=a3, where p is the planet's orbital period in years and a is its average orbital distance in AU.

When was Galileo formally vindicated by the church?

1922

What is Kepler's second law?

2. As a planet moves around its orbit, it sweeps out equal areas in equal times. *This means that a planet travels faster when it is nearer to the sun and slower when it is farther from the sun.*

Hallmarks of science #3

A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.

What is an ellipse?

An ellipse looks like an elongated circle.

Which of the following orbits shows the planet at aphelion?

Aphelion is the point in a planet's orbit that is farthest from the Sun.

True or false: Galileo also saw 5 moons orbiting Jupiter, proving that not all objects orbit Earth.

False, he saw 4

mass energy

E=mc^2

How did Galileo solidify the Copernican revolution?

Galileo (1564-1642) overcame major objections to the Copernican view. Three key objections rooted in the Aristotelian view were the following: 1. Earth could not be moving because objects in air would be left behind. 2. Noncircular orbits are not "perfect" as heavens should be. 3. If Earth were really orbiting Sun, we'd detect stellar parallax

Who were the first known to make models of nature?

Greeks

What happened in 1824 to Galileo?

His book on the subject was removed from the Church's index of banned books.

Which of the following paths could not be a real orbit for a planet around the Sun?

Kepler's first law tells us that the orbit of a planet must be an ellipse with the Sun at one focus. Therefore, the path that shows the Sun in the center of the ellipse, rather than at a focus, cannot be the real orbital path of a planet. (Note that the circular path is allowed because a circle is an ellipse in which both foci are at the center.)

Basic Types of Energy

Kinetic (motion) Radiative (light) Stored or potential - Energy can change type but can't be created or destroyed - Energy is measured in calories or joules

The following diagrams all show the same star, but each shows a different planet orbiting the star. The diagrams are all scaled the same. (For example, you can think of the tick marks along the line that passes through the Sun and connects the nearest and farthest points in the orbit as representing distance in astronomical units (AU).) Rank the planets from left to right based on their average orbital distance from the star, from longest to shortest. (Distances are to scale, but planet and star sizes are not.)

Note that the line that passes through the star and connects the nearest and farthest points of the planet's orbit is called the major axis, and half this line is the semimajor axis — which we consider the planet's average distance from the star.

What is acceleration?

The rate at which velocity changes

Which of the following orbits has the largest semimajor axis?

The semimajor axis is half of the distance across the ellipse in its longest direction (which means half of the major axis), which is also the planet's average distance from the Sun. Therefore, the ellipse that measures the longest across is the one with the largest semimajor axis.

conservation of momentum

The total momentum of a system cannot change unless an external force is acting on them. - External = from environment - Interacting objects within the system can exchange momentum through equal and opposite forces.

True or false: Galileo's observations of phases of Venus proved that it orbits the Sun and not Earth.

True

True or false: Mass is a form of potential energy?

True

True or false: Our mathematical and scientific heritage originated with the civilizations of the Middle East?

True

The following diagrams are the same as those from Parts A and B. This time, rank the planets from left to right based on their average orbital speed, from fastest to slowest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality. (Distances are to scale, but planet and star sizes are not.)

This pattern illustrates another of the ideas that are part of Kepler's third law: Planets with larger average orbital distances have slower average speeds.

Closed system

Total momentum can't change - Total angular momentum can't change - Total energy can't change

True or false: A small amount of mass can release a great deal of energy?

True

Newton's First Law

an object moves at constant velocity unless a net force acts to change its speed or direction. * No net force = no acceleration No acceleration = no net force*

Tides and Phases

size of tides depends on the phase of the moon

speed formula

speed = distance/time (units of m/s)

What is velocity?

speed and direction

Over a 10 week period, Mars appears to do what?

stop, back up, then go forward again.

How did the Greeks explain planetary motion?

underpinnings of the Greek geocentric model: a. Earth at the center of the universe b. Heavens must be "perfect"-objects move on perfect spheres or in perfect circles.

Net force

- Net force means the sum of all forces acting on a body -changes momentum - usually mass is constant so velocity changes -> acceleration

Gravitational potential energy depends on what?

- mass (m) - the strength of gravity (g). - the distance an object could potentially fall.

How did Copernicus challenge the Earth-centered idea?

-Copernicus proposed the Sun-centered model (published in 1543). - He used this model to determine the layout of the solar system (planetary distances in AU) - BUT the model was not any more accurate than the Ptolemaic model in predicting planetary positions because it still used perfect circles.

Changing an orbit

-Friction or atmospheric drag -A gravitational encounter

Preserving the ideas of the Greeks

-The Muslim world preserved and enhanced the knowledge they received from the Greeks while Europe was in its Dark Ages -Al-Mamun's House of Wisdom in Baghdad was a great center of learning around A.D. 800 -With the fall of Constantinople (Istanbul) in 1453, Eastern scholars headed west to Europe, carrying knowledge that helped ignite the European Renaissance.

conservation of energy

-The total energy of a system cannot change unless it interacts with its environment - Interacting objects within the system can exchange energy - Energy can also be converted from one type to another Energy can be neither created nor destroyed. -It can change form or be exchanged between objects. - The total energy content of any isolated system must always stay the same.

Why are astronauts weightless in space?

-There is gravity in space. -Weightlessness is due to a constant state of free-fall. a. Weight is what we feel when something keeps us from falling freely

Conservation of Angular Momentum

-angular momentum= mass X velocity X radius - The angular momentum of an object cannot change unless an external twisting force (torque) is acting on it. - Earth experiences no twisting force as it orbits the Sun, so its rotation and orbit will continue indefinitely.

kinetic energy

-energy of motion - An object's kinetic energy is proportional to its mass and to the square of its speed a. K = ½ m v2 - If an object is moving, it has kinetic energy

Momentum

-mass x velocity - momentum is constant unless a net force acts on the object.

How to calculate the circumference of the Earth

7/360 X (circumference of Earth) = 5000 stadia Circumference of Earth= 5000 X 360/7 stadia which is approximately 250,000 stadia

Which of the following orbits is the most eccentric?

Eccentricity is a measure of how "stretched out" an ellipse is. A perfect circle has zero eccentricity, and the most stretched out ellipse has the largest eccentricity.

Hallmarks of science #1

Modern science seeks explanations for observed phenomena that rely solely on natural causes *A scientific model cannot include intervention*

Motion

Where = position when = time

Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's second law? Check all that apply. a. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. b. Venus orbits the Sun faster than Earth orbits the Sun. c. All the planets orbit the Sun in nearly the same plane. d. Inner planets orbit the Sun at higher speed than outer planets. e. Earth is slightly closer to the Sun on one side of its orbit than on the other side. f. The Sun is located slightly off-center from the middle of each planet's orbit.

a

The video states that the planetary orbits are shown to scale. Which statement correctly describes the way the planet sizes are shown compared to their orbits? a. The planets are all much too large compared to their orbits. b. The planets should all be about twice as large as shown. c. Jupiter is shown correctly to scale with its orbit, but all the other planets are too large. d. The planet sizes are correctly shown on the same scale as the orbits.

a

Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's first law? Check all that apply. a. Earth is slightly closer to the Sun on one side of its orbit than on the other side. b. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. c. The Sun is located slightly off-center from the middle of each planet's orbit. d. All the planets orbit the Sun in nearly the same plane. e. Venus orbits the Sun faster than Earth orbits the Sun. f. Inner planets orbit the Sun at higher speed than outer planets.

a, c

Which of the following can you observe about Venus with the naked eye? Select all that apply. a. Venus sometimes shines brightly in the western sky shortly after sunset b. Venus is visible at midnight when it is in its full phase c. When Venus is brightest, it is visible all night long d. Venus sometimes shines brightly in the eastern sky shortly before dawn

a,d

Based on the video, which Venus phase would be impossible to see (from Earth) if Venus orbited Earth as described in Ptolemy's Earth-centered model? a. gibbous (nearly full) b. new c. crescent on the left side d. crescent on the right side

a.

Why do the planets orbit the Sun (i.e. why don't they crash into the Sun)? a. Although the planets experience a force of gravity from the Sun, since they are moving, their trajectories bend around the Sun rather than lead directly into the Sun. b. There is no gravity in space. c. All astronomical objects move in circular orbits.

a. Although the planets experience a force of gravity from the Sun, since they are moving, their trajectories bend around the Sun rather than lead directly into the Sun.

Earth is slightly closer to the Sun in January than in July. How does the area swept out by Earth's orbit around the Sun during the 31 days of January compare to the area swept out during the 31 days of July? a. Both areas are the same. b. The area swept out in July is larger. c. The area swept out in January is larger.

a. Both areas are the same.

Suppose two comets, comet A and comet B, were orbiting the Sun, having the same average orbital radii. If comet A had a higher eccentricity than comet B, which comet would, during some portion of its orbit, have the highest orbital speed? a. Comet A b. Comet B c. Both comets would have the same highest speed.

a. Comet A

You discover an asteroid that orbits the Sun with the same 1-year orbital period as Earth. Which of the following statements must be true? a. The asteroid's average (semimajor axis) distance from the Sun is 1AU. b. The asteroid shares the same orbit around the Sun as Earth. c. The asteroid will eventually collide with Earth. d. The asteroid has the same perihelion distance as Earth. e. The asteroid has a more eccentric orbit than Earth.

a. The asteroid's average (semimajor axis) distance from the Sun is 1 AU.

A planet is discovered orbiting the star 51 Peg with a period of four days (0.01 years). 51 Peg has the same mass as the Sun. Mercury's orbital period is 0.24 years, and Venus's is 0.62 years. The average orbital radius of this planet is a. less than Mercury's. b. between Mercury's and Venus's. c. greater than Venus's.

a. less than Mercury's

An original observation of Galileo's that helped to overturn the ancient Earth-centered model was a. the phases of Venus b.that planets move in elliptical orbits c. stellar parallax d. retrograde motion of planets in our sky

a. the phases of Venus

If Earth's orbit were very eccentric, but the average distance from the Sun were still 1 AU, its orbital period a. would still be one year. b. would be less than one year c. would be longer than one year.

a. would still be one year

According to Kepler's third law: a. Mercury travels fastest in the part of its orbit in which it is closest to the Sun. b. Jupiter orbits the Sun at a faster speed than Saturn. c. All the planets have nearly circular orbits.

b

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law: a. Earth travels faster in its orbit around the Sun in July than in January. b. Earth travels faster in its orbit around the Sun in January than in July. c. It is summer in January and winter in July.

b

How does its average distance compare to that of Pluto? a. Pluto orbits farther than Eris. b. Eris orbits farther than Pluto.

b

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

b

On (Figure 1), you can see Kepler's third law (p2=a3) from the fact that __________. a. the axes are labeled with values for p2=a3 b. the data fall on a straight line c. the planet names are labeled on the graph

b

When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been a. wrong. b. incomplete. c. really only a guess.

b

Which of the basic types of energy is illustrated when you stand on a ladder? a. kinetic b. potential c. radiative d. heat e. None of the above

b

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

b

Which of the following are the three key hallmarks of science? a. Science progresses through careful application of what is called the scientific method. b. Science progresses through the creation and testing of models of nature that explain the observations as simply as possible. c. Modern science seeks explanations for observed phenomena that rely solely on natural causes. d. Scientific models must be structured so that they can be proved true by a single good observation or experiment. e. Models must make testable predictions that will force us to revise or abandon the model if they do not agree with observations.Scientific models are miniature representations of reality.

b,c,e

An asteroid orbits the Sun at an average distance a= 4 AU. How long does it take to orbit the Sun? a. 4 years b. 8 years c. 16 years d. 64 years *p2=a3

b. 8 years

Two planets are observed going around a star. Planet Xoron has an orbital period that is twice as long as planet Krypton. Which planet has a shorter average orbital radius? a. Planet Xoron b. Planet Krypton c. Both planets have the same average orbital radius. d. There's not enough information to determine.

b. Planet Krypton

Why wasn't the Sun-centered model of Copernicus immediately adopted after he proposed it? a. observations made with telescopes ruled it out b. it was not noticeably more accurate than the old Ptolemaic model c. Aristarchus had already formulated a Sun-centered model some 1500 years earlier. d. it featured the Earth at the center, which had already been ruled out by observations

b. it was not noticeably more accurate than the old Ptolemaic model

A compact car and a large truck have a head-on collision. Which one of the following is FALSE? a. The force of the car on the truck is equal and opposite to the force of the truck on the car. b. The momentum transferred from the truck to the car is equal and opposite to the momentum transferred from the car to the truck. c. The change of velocity of the car is the same as the change of velocity of the truck.

c

Approximately how fast is Jupiter orbiting the Sun? a. 20 km/s b. 10 km/s c. a little less than 15 km/s d. cannot be determined from the information provided

c

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

c

Is the force that Earth exerts on you larger, smaller, or the same as the force you exert on it? a. Earth exerts a larger force on you. b. You exert a larger force on Earth. c. Earth and you exert equal and opposite forces on each other

c

Tycho Brahe's contribution to astronomy included: a. inventing the telescope. b. proving that Earth orbits the Sun. c. collecting data that enabled Kepler to discover the laws of planetary motion.

c

When we say that a planet has a highly eccentric orbit, we mean that: a. it is spiraling in toward the Sun. b. its orbit is an ellipse with the Sun at one focus. c. in some parts of its orbit it is much closer to the Sun than in other parts.

c

Which of the following is not true about a scientific theory? a. A theory must explain a wide range of observations or experiments. b. Even the strongest theories can never be proved true beyond all doubt. c. A theory is essentially an educated guess.

c

Which of the following statements is an example of science and democracy working productively together? a. Membership in a scientific review panel is primarily based on scientific expertise, and secondarily on religious and political affiliation. b. A study with an anonymous funding source determines that all drugs made by a certain company are safe and effective. c. NASA scientists are required to make their data public within one year of acquiring the data, regardless of the status of the scientific project. d. A government appointee edits the conclusions of a scientific panel to reflect the opinion of the political party currently in power.

c

As a comet orbits around the Sun, its maximum speed is twice its minimum speed. What can we say about its orbit? a. The eccentricity of the orbit must be over 0.95. b. The orbit is nearly circular. c. The comet is twice as far from the Sun at aphelion as at perihelion. d. The orbit cannot be an elipse.

c. The comet is twice as far from the Sun at aphelion as the perihelion

If an astronomer claims to have discovered an object with a very eccentric orbit, which of the following best describes the orbital trajectory of the object? a. It looks like a figure 8. b. It is circular. c. It looks like a very squashed oval. d. None of the above.

c. it looks like a very squashed oval.

In Ptolemy's Earth-centered model, when would Venus appear directly behind the Sun as viewed from Earth? a. when it is in a crescent phase b. when it is in farthest from Earth c. when it is in closest to Earth d. never

d

Uranus, not shown on the graph, orbits about 19 AUAU from the Sun. Based on the graph, its approximate orbital speed is between about __________. a. 20 and 25 km/s b. 15 and 20 km/s c. 10 and 15 km/s d. 5 and 10 km/s

d

What produces acceleration in a car? a. The gas pedal b. The brake c. The steering wheel d. All of the above

d

Who is Dr. Fang, according to the information provided in the article? a. A Chinese Einstein scholar who doubts the Big Bang theory. b. A Chinese physicist who marched in the 1989 Tiananmen Square student uprising. c. An Einstein scholar who spent most of his life under house arrest in China. d. A teacher, from China, now at the University of Arizona, who favors the Big Bang theory.

d

Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p2=a3p2=a3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law? Check all that apply. a. The Sun is located slightly off-center from the middle of each planet's orbit. b. All the planets orbit the Sun in nearly the same plane. c. Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. d. Earth is slightly closer to the Sun on one side of its orbit than on the other side. e. Venus orbits the Sun faster than Earth orbits the Sun. f. Inner planets orbit the Sun at higher speed than outer planets.

e, f

What is a scientific theory?

A scientific theory must: a. Explain a wide variety of observations with a few simple principles b. Be supported by a large, compelling body of evidence c. NOT have failed any crucial test of its validity

Darwin's theory of evolution meets all the criteria of a scientific theory. This means: A. Scientific opinion is about evenly split as to whether evolution really happened. B. Scientific opinion runs about 90% in favor of the theory of evolution and about 10% opposed. C. After more than 100 years of testing, Darwin's theory stands stronger than ever, having successfully met every scientific challenge to its validity. D. There is no longer any doubt that the theory of evolution is absolutely true.

C. After more than 100 years of testing, Darwin's theory stands stronger than ever, having successfully met every scientific challenge to its validity

Each of the following diagrams shows a planet orbiting a star. Each diagram is labeled with the planet's mass (in Earth masses) and its average orbital distance (in AU). Assume that all four stars are identical. Use Kepler's third law to rank the planets from left to right based on their orbital periods, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality. (Distances are to scale, but planet and star sizes are not.)

Kepler's third law tells us that the orbital period of the planet depends on its average distance from its star, but not on the planet's mass. As Newton later showed with his version of Kepler's third law, this is actually an approximation that works well whenever the planet's mass is small compared to the mass of the star.

Mass vs. Weight

Mass—the amount of matter in an object - Measured in kilograms, or grams • Weight—the force that a scale measures - Measured in newtons or pounds *A 200 lb person on Earth has a mass of 91 kg

As you learned in the video, Galileo's observations of Venus in gibbous (nearly full) phase showed conclusively that Venus orbits the Sun, not Earth. Which figure shows Venus's position when Galileo saw it in gibbous phase?

Notice that the gibbous phase occurs when Venus is farther from Earth than the Sun, and this could never happen in Ptolemy's system. That is how Galileo concluded that Venus must orbit the Sun.

What did the Greeks try and explain with their models?

Patterns in nature without resorting to myth or supernatural.

How does the Ptolemaic model explain retrograde motion?

Planets really do go backward in the model.

The following diagrams are the same as those from Part A. This time, rank the planets from left to right based on the amount of time it takes each to complete one orbit, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality. (Distances are to scale, but planet and star sizes are not.)

Recall that the time it takes a planet to complete an orbit is called its orbital period. The pattern found in this Part illustrates one of the ideas that are part of Kepler's third law: Planets with larger average orbital distances have longer orbital periods.

True or false: Angular momentum explains why objects rotate faster as they shrink in radius

True

Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model? a. It allowed calculation of the orbital periods and distances of the planets. b. It made significantly better predictions of planetary positions in our sky. c.It offered a more natural explanation for the apparent retrograde motion of planets in our sky.

b

"A huge fleet of alien spacecraft will land on Earth and introduce an era of peace and prosperity on January 1, 2035." a. The claim can be evaluated scientifically by seeing whether or not the aliens show up on the appointed date. b. This claim can be evaluated scientifically by predicting whether the aliens will introduce an era of peace and prosperity. c. The claim can't be evaluated scientifically as we do not know the true purpose of the aliens arriving. d. The claim can't be evaluated scientifically as we do not whether the aliens will arrive on Earth on the appointed date.

a

Kepler's third law is often stated as p2=a3. The value a3 for a planet is shown on __________. a. the horizontal axis of Figure 1 b. the vertical axis of Figure 1 c. the horizontal axis of Figure 2 d. the vertical axis of Figure 2

a

Suppose (Figure 1) showed a planet on the red line directly above a value of 1000 AU3AU3 along the horizontal axis. On the vertical axis, this planet would be at __________.

b. 1000 years^2

All of the following statements are true. Which one can be explained by Kepler's third law? a. All the planets orbit the Sun in nearly the same plane. b. Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun. c. Earth is slightly closer to the Sun in January than in July. d. Venus orbits the Sun at a faster orbital speed than Earth. e. The Sun is not in the precise center of Saturn's orbit.

d. Venus orbits the Sun at a faster orbital speed than Earth.

The Moon takes roughly 28 days to complete one orbit around Earth. If the orbital radius of the Moon were twice its actual value, its orbital period would be a. less than 28 days. b. roughly 28 days. c. roughly 56 days. d. more than 56 days.

d. more than 56 days

What is the measurement from Syene to Alexandria?

distance is approximately 5000 stadia with and angle of 7 degrees

Choose the statement that best reflects the author's main point in this editorial. a. Science is known to be arrogant and materialistic, with no values whatsoever. b. Barack Obama has clearly demonstrated that his administration has been good for science. c. Scientists behave like ants swarming over an anthill, and drink lots of airport coffee. d. People who make incorrect scientific conclusions should be sent to prison. We'd get to the right answers a lot faster that way. e. Science and democracy rely on freedom and on each other to flourish.

e

Which of the following is true? a. You can have acceleration not equal zero, but velocity equal to zero b. You can have acceleration equal to zero, but velocity not equal to zero c. You can accelerate without changing your speed d. a and b e. a, b, and c

e

Newton's version of Kepler's third law

p^2 = 4π2/ G(M1 + M2 ) a^3 p= orbital period (seconds) a= average orbital distance between centers (meters) (M1 + M2)= sum of object masses (kilograms)

If a planet travels in a circular orbit without speeding up or slowing down, is it accelerating?

yes