Astronomy 1 HW (TCC)
Rank the following in order of size, from smallest to largest.
1. The radius of earth 2. A light-minute 3. The distance from Earth to the Sun 4. A light-hour 5. The radius of the Solar System 6. A light-year
Earth's; Moon
A lunar eclipse occurs when the ________ shadow falls on the ________.
the less massive one
If you use the same force to push on two different cars, which will have the bigger acceleration?
[1 being smallest and 3 being largest] 1. A decorative Styrofoam Apple 2. An apple 3. A decorative gold "apple"
Suppose that you drop the following objects (all of the same shape and size) off of a tall tower. Rank the objects in terms of the gravitational force on them, from smallest to largest.
If your hypothesis has passed nine tests, but fails the tenth one, what do you do?
Change the hypothesis or create a new one, then come up with new predictions and conduct more tests.
The highs would be higher and the lows would be lower.
If the Moon had twice the mass that it does, how would the strength of the lunar tides change?
Occam's razor states that
if two hypotheses fit the facts equally well, choose the simpler one.
increase by a factor of 4.
If the distance between Earth and the Sun were cut in half, the gravitational force between these two objects would
[1 Carrying the most energy and 4 carrying the Least] 1. Blue 2. Yellow 3. Orange 4. Red
The bright, colorful "stripes" of a rainbow such as the one shown here follow a particular order. Rank each color of the rainbow by how much energy is carried by its electromagnetic waves, from highest to lowest.
A light-year is a measure of
distance
the composition of any gas between the light-emitting "surface" of the star and the observer
Observations of excited gas in the lab show that every element, molecule, and ion has its own unique set of possible electron energy levels, as shown in the emission spectra below. Based on this fact, what can we find from the wavelengths of absorption lines seen in the spectrum of a star?
- The Sun rises earlier and sets later in July in the Northern Hemisphere. - Sunlight is more concentrated in the Northern Hemisphere in July.
What are the two pieces of information that must be considered to explain the seasons?
midnight.
You see the full Moon on the meridian. From this information, you can determine that the time where you are is
Order the steps in the scientific method by dragging each label to the corresponding target.
(Answer in order [top down] D,B,A,C) D. Start with an observation or idea. B. Suggest a hypothesis A. Make a prediction. C. Perform a test, experiment, or additional observation.
the car you pushed with the larger force
If you push with a different force on two cars of the same mass, which car will have the bigger acceleration?
Yes. It is changing its direction of motion all the tim
Imagine a planet moving in a perfectly circular orbit around the Sun. Is this planet experiencing acceleration?
Earth's year would be shorter.
Imagine that Earth were in a stable orbit at its current distance from the Sun, but around a different star that had twice the mass of the Sun. Which of the following would have to be true?
Research has supported the hypothesis that the wind is responsible for the motion of sailing rocks. There is evidence that wind can set the rocks moving when the ground becomes muddy or when thin layers of ice form beneath the rocks. This scenario has not been falsified by any tests conducted so far, and it is currently the favored explanation within the scientific community. What is the next step in the scientific process?
Make further predictions about this hypothesis and conduct more tests, abandoning or revising the hypothesis if any of the tests are failed.
[1 being the largest semi-major axis and 4 being the smalleset ] 1. A planet with a period of 2 Earth years 2. A planet with a period of 1 Earth year 3. A planet with a period of .5 Earth Years 4. A planet with a period of 84 Earth days
Place the following in order from largest to smallest semimajor axis.
[1 being Smallest and 4 being the Largest] 1. An object with a mass of 15kg orbiting the Earth at the same time distance as the Moon 2. An object with a mass of 5kg orbiting the Earth halfway to the Moon 3. An object with a mass of 20kg orbiting the Earth one-quarter of the way to the Moon 4. An object with a mass of 10kg orbiting Earth jsut above Earth's Surface
Rank the following objects in order of their circular speeds from smallest to largest.
High tide : 0⁰ 180⁰ Low tide : 90⁰ 270⁰
Sort the positions marked on the diagram of Earth into categories based on whether they are experiencing high or low ocean tides when the Moon is in the location shown. You may neglect the effects of Earth's rotation.
the orbit of the Moon around the Earth
Subsequent semi-diurnal (twice daily) tides happen precisely once every 12 hours and 25 minutes. Given what you know of the motions of the Earth and Moon, where is this extra 25 minutes likely coming from?
A hotter star will be brighter and bluer than a cooler star.
The light from objects that glow because they are warm (like people, planets, and stars) is distributed by wavelength in a particular way, called a blackbody spectrum. Using this interactive figure (requries Flash), experiment with how a blackbody spectrum changes with an object's surface temperature. Note that flux increases as an object gets brighter, and that the scale of the graph may be changing to indicate this, even if the curve doesn't appear to change. See the hint for tips on using the figure. Based on your observations, which one of the following is correct?
- The energy of the light would decrease. - The frequency of the light would decrease.
The nature of light is rather unique: It acts like both a particle (called a photon) and a wave that can propagate energy even through empty space. Navigate to the interactive figure in Section 2 of this animation, as shown below, to see how changing the amplitude, wavelength, speed, and frequency of a light wave affects its properties. Choose all of the effects that would automatically happen if the wavelength of light were increased.
1. Segment A 2. Segment B 3. Segment C
The planet in the diagram shown is in an elliptical orbit around the Sun. Rank the average orbital speed of the planet at each shaded orbit segment. The areas in segments A, B, and C are equal.
When we are faced with more than one hypothesis that has not been falsified by the evidence, Occam's razor tells us that the one that makes the fewest assumptions is most likely to be correct. An assumption is a condition that must be true for our hypothesis to work, but that we cannot prove one way or the other. Which of the following hypotheses about the bizarre motion of sailing rocks relies on the fewest assumptions?
The wind moves the rocks.
Venus is traveling faster when it is at perihelion (the closest distance to the Sun) than when it is at aphelion (the farthest distance from the Sun).
Watch the AstroTour on Kepler's Laws and choose the statement below that directly follows from Kepler's second law of planetary motion.
predicting planetary positions as a function of time
Watch the AstroTour on Kepler's Laws, focusing on Kepler's third law of planetary motion. What is this law useful for?
at three times the distance, the intensity is 1/9 as great.
Watch the Astronomy in Action video about the inverse square law and answer the following question. The "square" in the inverse square law for intensity of light means that
surface area increases like the radius of a sphere multiplied by itself.
Watch the Astronomy in Action video about the inverse square law, and answer the following question. The "square" in the inverse square law comes from the fact that
[1 being Approaching 3 being Receding] 1. Blueshifted 2. Rest wavelength 3. Redshifted
A comet is approaching Earth at a known velocity. Indicate the proper sequence that describes the wavelength of light you measure as it first approaches, then passes, and finally recedes from Earth.
North
Based on this information, determine where you would expect to find Polaris in your local sky when you are standing at the equator.
The stars appear to move westward from one night to the next.
Celestial motions over time periods longer than a day are less obvious. Say you went out at exactly the same time each night and looked at the sky, noting the position of a specific set of stars at that time with respect to reference objects on Earth, such as trees and buildings. The following figure shows how the stars would change position. Based on this figure, what is the most correct conclusion?
- The stars closest to Polaris move in smaller circles. - All of the stars move in a counterclockwise path around Polaris.
Examine the following figure, which demonstrates star trails that would be visible in a photo centered on the North Star (Polaris) when the camera's shutter is left open to reveal the path the stars are taking as they move during part of one night.
The Earth's gravity pulls downward on the person, and the person's gravity pulls upward on the Earth.
Newton determined that the force of gravity on an object is proportional to its mass, causing its mass to be canceled out (Newton's second law) and resulting in a constant acceleration. If the laws of physics are universal, then Newton should be able to apply his discoveries about gravity on Earth to the motion of the planets in our Solar System. Newton's third law says that for every force there is an equal reaction force in the opposite direction. What does this imply about the force of gravity associated with a person standing on the Earth?
The scientific method works well when it is used properly, but ignoring the rules, not looking at results in an objective manner, and flat-out cheating can lead to bad science. We must therefore be careful along every step of the scientific process, including the selection of which evidence to consider for a hypothesis. Consider the following scenario: A person sees a UFO in the middle of the night while walking alone on the beach. No other evidence of the UFO is left behind at the scene. Would the anecdotal verbal account from this witness be valid scientific evidence of the event?
No, because follow-up tests conducted by others cannot verify it.
The tilt of the Earth's rotation axis to its orbit around the Sun causes parts of the Earth to experience more direct illumination from the Sun and longer days during the summer than the winter.
What causes the seasons?
365 days
About how long does it take Earth to orbit the Sun?
29 days
About how long does it take the Moon to orbit Earth?
the same; mass doesn't change.
Compared to your mass on Earth, on the Moon your mass would be
They are too slow.
Why don't we see cars as bluer when they approach and redder when they recede?
Place the following numbers in order, from smallest to largest.
1. 7 x 10⁻¹² 2. 3 x 10⁻¹⁰ 3. 700,000,000 4. 8 x 10⁸ 5. 40 billion 6. 2 x 10¹¹
Based on the seasonal views of the sky in the diagram shown, is it more likely to be summer or winter when the following constellations are visible? (For the purposes of this problem you may ignore the fall and spring views.)
1. Winter - Orion - Canis Major 2. Summer - Scorpius - Cygnus 3. Need more Information - Ursa Major - Pegasus
There are many perfectly valid subjects that cannot be studied using the scientific method. Which of the following cannot be studied in a scientific way?
1. the relative tastiness of various foods 2. religion 3. art
[1 being Lower energy and 6 being Higher energy] 1. Radio 2. Infrared 3. Orange 4. Green 5. Ultraviolet 6. Gamma ray
Changing the wavelength of visible light changes its color. If the wavelength is decreased or increased outside of the range of wavelengths our eyes can detect, the light becomes invisible to us, but it is still fundamentally light. Examine the figure, which shows the entire electromagnetic spectrum and includes all types of light as a function of wavelength. Given what you learned from the figure, rank these types of light in order of increasing energy.
[1 being lowest and 4 being highest] 1. 1 Mearth / 2 Msolar / 2 AU 2.4 Mearth / 2 Msolar / 3 AU 3. 1 Mearth / 1 Msolar / 1 AU 4. 2 Mearth / 1 Msolar / 1 AU
Compare the gravity between these pairs, each consisting of an Earth-like planet and its star. You are given the mass of the planet in Earth masses, the mass of the star in Sun masses, and the distance in AUs.
- If light has infinite speed, an eclipse would be seen to happen at the same time regardless of how far away Earth is from Jupiter. - If light has finite speed, it would take longer for it to travel from Jupiter to Earth when Earth is farther from Jupiter.
Following the invention of the telescope, astronomers were able to measure the speed of light by observing Jupiter's moons passing behind Jupiter in their orbit and becoming eclipsed. Study the figure, which shows how someone on Earth can view Jupiter's moon's eclipses when Earth is closer to or farther from Jupiter, and determine which of the following are correct.
along the line between the planet and the star, closer to the planet.
For a system in which a planet orbits a star, the center of mass is located
The Moon is much less massive than the Earth, so it will take longer for it to slow the Earth into synchronous rotation.
The Moon's bulge used to be nonaligned with the line connecting the Earth and the Moon, just like Earth's bulge is now. Earth pulled on the bulge of the Moon, slowing its rotation until it was aligned with the Earth. Therefore, we always see only one side of the Moon from Earth (synchronous rotation, as shown in the figure). If these tidal forces naturally cause synchronous rotation for each object, why is the Moon currently in synchronous rotation with the Earth, but the Earth is not in synchronous rotation with the Moon?
The stars must be so distant that their parallaxes are too small for the ancient Greeks to have been able to measure with their technology.
The ancient Greeks predicted that if the Earth revolved around the Sun, they would observe stellar parallax, as illustrated in the figure. However, they did not measure stellar parallax—the stars did not appear to move back and forth at all over the course of a year. What is the most likely reason for this apparent lack of motion?
"We are stardust" means that
the atoms in our bodies have passed through (and in many cases formed in) stars.
Place each listed action in its proper spot on the scientific method flowchart.
- Start with an observation or an idea. C. You notice that a firefly glows. - Suggest a hypothesis. B. You think a firefly may glow because it is on fire. - Make a prediction E. You determine that if a firefly is on fire it will burn paper held up to it. - Perform a test, experiment, or additional observation and analyze data. A. You capture a firefly and hold paper to it to see if the paper will burn. If the test observation does not support the hypothesis, make more observations, receive the hypothesis, or choose a new one. D. Paper does not burn when held up to a firefly.
The scientific method, when used properly, helps us sift through personal biases and misconceptions to gain a more complete and correct understanding of the way things are. Review the basic steps of the scientific method in the following figure. We can use this method to come to a better understanding of a natural phenomenon seen in Death Valley, California, called "sailing rocks." The following picture shows one of these rocks, which appears to move on its own. We can create a number of hypotheses to explain this phenomenon. A scientific hypothesis must follow certain rules: It must rely only on natural explanations, it must be verifiable (can be proven false if it is false), and it must be able, in principle, to be tested by anyone. The following are all potential explanations for the motion of sailing rocks, but not all of them are scientific hypotheses given the rules listed above. Which ones are not scientific hypotheses?
1. Magic 2. God 3. Ghosts
This plot shows the number of viruses that exist at each particular time step as they reproduce. Using the average slope of the data per time step shown on the graph, rank the periods of viral growth from highest to lowest.
1. Time step = 10 - 11 2. Time step = 7 - 10 3. Time step = 5 - 73 4. Time step = 0 - 5 (#1 is highest slope #4 is lowest)
bound; unbound
An object in a(n) __________ orbit in the Solar System will remain in its orbit forever. An object in a(n) __________ orbit will escape from the Solar System.
[1 being Weakest and 3 being Strongest] 1. First Quarter 2. Waning Gibbous 3. New Moon
Earth's tides are caused by the gravitational pull of both the Sun and the Moon. Rank the strength of the combined tidal forces exerted on Earth, and thus the height of the tides, when the Moon is in the following phases listed.
1. Winter Solstice 2. Vernal Equinox 3. Summer Solstice 4. Autumnal Equinox
Four special days mark the passage of the seasons. Assuming you live in the Northern Hemisphere, place these days in sequence as they occur in the year, beginning with the one that marks the official start of winter.
The force of gravity is stronger closer to the Sun.
Newton developed a universal law of gravitation that can be used under most circumstances, not just for objects on the surface of the Earth. Here is the law: F = G (m1 * m2 / r2) where G is a constant. Think about what happens when you increase and decrease each of the variables in Newton's equation for the gravitational force between two objects of mass m1 and m2, a distance r from one another. You can use this interactive figure (requires Flash) to help visualize the changes. Given your results, what is the likely cause of Kepler's observation that planets travel faster when they are closer to the Sun?
Obeys Kepler's 3rd Law : Asteroid with A^3 = 10^4, P^2 = 104 Asteroid with A^3 = 1, P^2 = 1 Too fast : Asteroid with A^3 = 10^4, P^2 = 10^-1 Too slow : Asteroid with A^3 = 10, P^2 = 10^3
The following graph represents how the period (P) and average distance from the Sun (A) of planets in our Solar System are related according to Kepler's third law. Since the behavior of the gravitational force is universal, the line drawn through the planets shows a relationship that is applicable to all objects orbiting the Sun, regardless of their type. Indicate whether each of the following hypthetical asteroids would either obey Kepler's third law for our Sun or would be moving too fast or too slow for it. In all cases A is in AU and P in years. (Hint: 100 = 1, 101 = 10, 102 = 100, etc.)
Fred : - Red light Velma : - Blue light Daphne : - Green light
The image provided shows a light source moving relative to three different observers: Fred, Velma, and Daphne. If the light source is emitting green light and moving with sufficient speed, identify which colors each person could possibly see.
The constellations that can be seen differ with the seasons. Order the constellations according to the seasons in which they can be seen in the evening sky by Northern Hemisphere observers.
1. Corvus 2. Sagittarius 3. Sculptor 4. Lepus
Identify each of the following six planets and order them by distance from the Sun. You may need to scroll right to view all of the images.
1. Earth 2. Mars 3. Jupiter 4. Saturn 5. Uranus 6. Neptune
Falsely presenting subjects as if they have been verified through scientific methods is called pseudoscience. In pseudoscience, the process of gathering and evaluating evidence has failed to follow the scientific method in one or more ways. Match each statement with the closest corresponding scientific rule it is breaking. 1. "This natural phenomenon was caused by extraterrestrial visitors who leave no measurable trace of their presence." 2. "I was given the answer to this question in a prophetic dream." 3. "This model is proven to be correct because it makes accurate predictions 75 percent of the time."
1. Hypotheses must be verifiable. 2. Tests must be repeatable by anyone. 3. Hypotheses must be abandoned or revised if they fail a single test.
Over the course of a year, stars should appear to move back and forth, with stars closer to us moving a larger distance.
The heliocentric model offered a simple explanation for retrograde motion, but the ancient Greeks determined that it was incorrect. Not only did the Earth feel like it was not moving, but the paradigm of the time was that Earth was special and thus had to be at the center of the universe. They did, however, consider the possibility that their paradigm was incorrect by testing the heliocentric model through the prediction that stellar parallax would exist if the Earth orbited around the Sun. Study the figure, which shows the line of sight between Earth and two stars. Choose the answer that most closely matches what we would observe in our sky, according to this figure, if the Earth orbits around the Sun.
The process of making predictions and testing scientific models never ends, as there is always the possibility that some future experiment or observation will show that a previously well-accepted model doesn't actually work under all circumstances. However, if a hypothesis is backed up by a very large body of evidence and has never failed a test, it may be elevated to the status of a theory. According to the scientific method, choose all of the following statements that are correct.
1. All theories have enough supporting evidence behind them that we can move forward under the assumption that they are correct unless some future test proves that this is not the case. 2. A theory has a higher probability of accurately modeling a natural phenomenon than a hypothesis does.
Suppose you lived on the planet named "Tau Ceti e" that orbits Tau Ceti, a nearby star in our galaxy. How would you write your cosmic address?
1. Tau Ceti e 2. Tau Ceti 3. Milky Way Galaxy 4. The Local Group 5. Virgo Supercluster 6. Universe
Unbound : Orbit 3 Orbit 4 Circular : Orbit 1 Elliptical : Orbit 2
According to the object orbits shown on the vertical axis at left of the graph, identify each orbit as either unbound, circular, or elliptical.
The heliocentric model explains retrograde motion because Mars only appears to move backward as Earth passes it in its orbit around the Sun.
How does the heliocentric model explain the retrograte motion of Mars?
For Hypothesis : - Closer light source has stronger intensity. - Earth's orbit is elliptical. Against Hypothesis : - Earth's closest approach to Sun is in January. - S and N hemispheres have opposite seasons
Determining what causes the seasons is not as straightforward as determining what causes day and night. We can begin by suggesting hypotheses and then testing them for their validity. Let's start with the hypothesis that the seasons are caused by a variable distance between the Earth and the Sun. Sort the observations or physical laws below according to whether they argue for or against this hypothesis.
toward Earth
Imagine that you observe a star-planet system, edge-on. When the planet is moving away from Earth, in which direction is the star moving?
Make predictions from Copernicus's model, and verify them with observations.
In 1500s, Copernicus reintroduced the heliocentric model that the ancient Greeks had rejected, and it began to gain favor among some scientists. He suggested that the planets all orbit around the Sun in perfect circles, as shown in the figure to the right. This offers a much more elegant explanation of retrograde planetary motion than the geocentric model. What would be the next step in the scientific process for the Copernican heliocentric model?
- a precise amount of energy. - more energy than to jump up one energy level. - a bluer photon than to jump up one energy level.
In order for an electron to jump up two energy levels in an atom at once, it requires
[1 being the Least Energy and 6 Being the Most] 1. Radio Waves 2. Infrared 3. Red Visible Light 4. Blue Visible Light 5. X-Rays 6. Gamma Rays
Rank the types of radiation in order of their energy, from least to greatest.
The Sun will appear to be higher above the southern horizon in the summer than in the winter.
The apparent path the Sun takes through the constellations over the course of a year is called the ecliptic. As seen in the figure shown, the Sun is in a different position on the ecliptic at different times of year. Assuming you are in the Northern Hemisphere, how would you expect the location of the Sun in your local sky at noon to differ from season to season?
Long days, short nights : position 3 Short days, long nights : position 1 Equal day and night : position 2, position 4
The diagram shows the Earth in different positions in its orbit around the Sun, with an exaggerated axial tilt. North is up and South is down. Sort each of the numbered positions into the category that describes its relative length of daylight in the Southern Hemisphere.
The Moon used to be closer to Earth than it is now.
There is friction between the layers of the Earth, which causes the tidal bulge to be dragged along as the Earth rotates, pulling it out of alignment with the line connecting the Moon and Earth.
exhibits retrograde motion.
When Earth catches up to a slower-moving outer planet and passes it in its orbit, in the same way that a faster runner overtakes a slower runner in an outside lane, the outer planet
The Sun appears to move across the constellations over the course of a year, ending where it started with respect to the background stars by the end of that period.
During the day, the Sun is too bright for us to see where it is located with respect to the constellations, but we can use our observations of stars at night to figure this out. Based on the way stars shift position over the course of a year, your knowledge of how the time of day is defined, and the fact that the same constellations are seen at the same place in the sky at the same time of night on a given day of the year, which of the following is most likely correct?
- There will be no change in the spectral lines of an object that is moving transversely from an observer. - An object moving toward an observer will have its spectral lines blueshifted.
The specific wavelength of a set of spectral lines depends not only the type of material that is creating them but also on the relative speed of that material to the observer. This is caused by the Doppler effect, which is demonstrated in this interactive figure (requires Flash). For tips on using the interactive figure, click on the hint. Experiment with this figure and use your observations to select all of the correct answers below. Note that blueshifted spectral lines appear shorter in wavelength than they otherwise would, and redshifted wavelengths appear longer.
more luminous; bluer
As a blackbody becomes hotter, it also becomes __________ and __________.
on opposite sides of the center of mass, traveling in opposite directions in space.
As two objects orbit one another, they are always
They are falling around Earth at the same rate as the shuttle.
Astronauts in a space shuttle can float while orbiting Earth. Why are these astronauts weightless?
Rank the given objects in order of increasing size. You may need to use the arrows on the side to scroll to see all of the images.
1. Earth 2. Solar System 3. Milky Way 4. Local Group 5. Supercluster
Rank the following in order of size, from smallest to largest distance. You may need to click the arrow icon to view all of the images.
1. Earth - Moon 2. Sun - Earth 3. Sun - Neptune 4. Sun - Proxima Centauri (the closest star to our Sun) 5. Earth's Sun - Milkyway Galaxy
he shift from day to night is caused by the rotation of the Earth around its axis.
From our point of view on Earth, it feels as if we are stationary and the celestial sphere and Sun are all rotating around us. In actuality, however, the Earth is moving, rotating on an axis that is tilted with respect to the orbit it takes around the Sun. Open the AstroTour called "The Earth Spins and Revolves." Watch the Introduction, and the first half of the Explanation (up until the interactive part). Then, choose one of the following conclusions that best explains the cause of the shift from day to night.
The geocentric model is wrong because it falsely predicts that Mars should always move in the same direction with respect to the stars.
From our vantage point on Earth, it looks like the Earth is stationary, and the Sun, Moon, stars, and planets are orbiting around us. Humans believed this geocentric (Earth-centered) view of the universe for the majority of history. The geocentric model of the universe looked like the left figure shown, with all celestial objects orbiting Earth in perfect circles. The brightest planets are visible to the naked eye, and they move through the background of the stars from one night to the next. Study the picture, which shows Mars's position with respect to the stars over the course of many nights. What can you conclude from this, assuming that the geocentric model holds that the Sun, Moon, and planets like Mars all orbit around Earth in simple circles?
- At latitudes closer to the poles, the difference in the Sun's illumination throughout the year is more extreme. - In the Northern Hemisphere, the Sun is lower in the sky in December than it is in June. - In the Northern Hemisphere, the length of the day is shorter in December than it is in June.
How does the changing position of the Sun on the ecliptic affect our view of the Sun in our local sky at different locations on Earth? In this interactive figure (Flash required) investigate how the path of the Sun changes in the local sky of a person at various latitudes on Earth. Then choose the following statements that match your observations. (See the Hint if you need tips on how to use the figure.)
blueshifted.
Imagine that you observe a star/planet system, edge-on. When the planet is moving away from Earth, the light from the star is
- If the light of the Sun were suddenly extinguished, we wouldn't notice it from Earth for over 8 minutes. - When we gaze at the Andromeda Galaxy, we are looking back in time to the way it used to appear millions of years ago. - There would be a noticeable delay in communications at the speed of light between Earth and astronauts on the Moon.
In a vacuum, light travels 300,000 km every second. Examine the following figure, which shows how long it takes for light to travel particular distances, and then scroll down to the question at the end. Based on the time frames given in the above figure, which of the following are implications of the finite speed of light?
The acceleration of all objects dropped from the tower is the same.
Isaac Newton developed a theory of gravity by first considering Galileo's experiment of dropping objects of different masses from the Leaning Tower of Pisa. Galileo found that, when air resistance is negligible, all objects took the same amount of time to hit the ground when dropped from the top of the tower.
According to the graphs shown, by how much did the number of viruses increase in four time steps? (Remember, we start out with a single virus.)
It went up 16 times.
Once we have come up with a number of plausible hypotheses to explain the "sailing rocks" phenomenon shown, what is the next step we should take, according to the scientific method?
Make predictions for each hypothesis, which will be observed if that hypothesis is correct.
Drag each label denoting length of time it takes light to travel from one location to another to the correct target.
Moon to Earth: 1.2 sec Earth to Sun: 8.5 min Pluto to nearest star: 4.3 years Across the length of the Milky way galaxy: 100,000 years
The force of gravity increases with increased mass.
Newton's second law says that the acceleration (a) of an object depends on its mass (m) by the equation: a = F / M F is the force that is causing the object to accelerate. In the case of dropping objects from a height, the force that causes them to accelerate toward the Earth is gravity. If the acceleration of objects dropped from a height does not depend on the object's mass (as shown by Galileo's experiment), what does this imply about the force of gravity?
The Earth's day will become longer with time.
Newton's third law says that if the Earth's bulge is pulling the Moon forward in its orbit, the Moon must be pulling with a reaction force back on the bulge. Given the sense of rotation in the figure, and the location of the Earth's bulge with respect to the Moon, what effect would you expect to come from this reaction force?
Once we have made predictions for a hypothesis, we need to test them. In the case of the "sailing rocks" phenomenon, scientists marked the positions of several rocks with stakes, returning periodically to record how the positions changed over the course of several years. They found erratic behavior—the amount of motion changed from year to year for each rock, and some rocks would remain still while nearby ones moved a large distance. Consider this information, and carefully examine these pictures of sailing rocks and their tracks. Consider the hypothesis that, although the land appears to be flat, there is enough of a slope that gravity is the only force causing the rocks to move. Based on the scientists' findings and the tracks shown, is this hypothesis verified?
No. The rocks' behavior is too eratic for gravity to be the only cause. Some other force that changes randomly with time must be involved.
[1 being the Longest wavelength 5 being the Shortest wavelength] 1. Radio waves 2. Infrared 3. Visible 4. Ultraviolet 5. Gamma rays
Rank the following in order of decreasing wavelength.
The hypothesis is falsified because some of the evidence is against it.
To explain the fact that summer is hotter than winter, we can hypothesize that seasons are caused by a variable distance between the Earth and the Sun at different times of the year. Now consider the following facts that relate to this hypothesis: - The Earth's orbit is elliptical (not a perfect circle). - The Southern Hemisphere experiences opposite seasons from the Northern Hemisphere. - The intensity of light from a source is stronger closer to the source. - The Earth's closest approach to the Sun is in January. Is the hypothesis that the seasons are caused by a variable distance between the Earth and the Sun verified or falsified by the evidence?
- Halley's Comet has a highly eccentric orbit. - Elliptical orbits cause a planet to sometimes be closer to and sometimes farther away from the Sun.
To test Copernicus's model, Tycho took meticulous measurements of the positions of the planets, and he hired Kepler to interpret the data. Kepler found that the geocentric model did not accurately predict the planets' positions, but neither did Copernicus's heliocentric model. He found that Copernicus's insistence that the planets' orbits were perfectly circular was the problem. If the orbits were instead ellipses, then the heliocentric model would have been able to very accurately predict the positions of the planets. This is known as Kepler's first law of planetary motion.
tidal locking
What causes the Moon to always keep the same face toward Earth?
- the velocity of the ball - the speed of the ball
When a ball is tossed in the air and reaches the top of its arc, which of the following quantities are zero?
gravity pulling downward
When the professor tosses the ball in the air, what forces are acting on it once it leaves her hand?
move farther away from the light source
When you turn on a lightbulb in a room, the entire room appears to flood with light at the same time. Your eyes cannot perceive light originating at the bulb and then moving outward from it. This either means that light has infinite speed (appears everywhere instantaneously), or it moves so fast that it is difficult to tell the difference. How might you improve your chances of detecting the motion of light if it moves at finite speed?
- speed toward or away from an observer - temperature - composition
Which of the following can astronomers determine from the spectrum of an object?
The planets would usually move west to east through the stars, but they appear to reverse direction when they are on the part of the epicycle that has motion opposite to that of the larger circle.
Which of the following most closely explains what we would see from Earth according to the geocentric model that includes epicycles?