astro 101 week 3 quiz
Leftover ice-rich planetesimals are called (a) comets. (b) asteroids. (c) meteorites.
(a) comets
How many of the planets orbit the Sun in the same direction as Earth does (a) a few (b) most (c) all
(c) all
What was the heavy bombardment, and when did it occur?
Early in the solar systems life when a majority of left over planetesimals bombarded with planets.
Use table 6.1, Which column tells you which planet has the shortest day? Are there notable differences in the length of a day for the different types of planets?
Rotation period. Jovian planets tend to have much shorter days due to how they were created.
About how old is the solar system? (a) 4.5 million years (b) 4.5 billion years (c) 4.5 trillion years
(b) 4.5 billion years
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) Earth travels faster in its orbit around the Sun in January than in July
Planetary orbits in our solar system are (a) very eccentric ellipses and in the same plane. (b) fairly circular and in the same plane. (c) fairly circular but oriented in every direction.
(b) fairly circular and in the same plane.
Compared to their values on Earth, on another planet your (a) mass and weight would be the same. (b) mass would be the same but your weight would be different. (c) weight would be the same but your mass would be different.
(b) mass would be the same but your weight would be different.
A car is acceleration when it is (a) traveling on a straight, flat road at 50 miles per hour. (b) traveling on a straight uphill road at 30 miles per hour. (c) going around a circular track at a steady 100 miles per hour.
(c) going around a circular track at a steady 100 miles per hour.
What is Jupiter's main ingredient? (a) rock and metal (b) hydrogen compounds (c) hydrogen and helium
(c) hydrogen and helium
When we say that a planet has a highly eccentric orbit, we mean that (a) it is spiraling towards 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
(c) in some parts of its orbit it is much closer to the Sun than in other parts
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be (a) twice as strong. (b) half as strong. (c) one-quarter as strong.
(c) one-quarter as strong
The recently discovered Eris orbits the Sun every 557 years. What is its average distance (semi-major axis) from the Sun? How does its average distance compare to that of Pluto?
67.69 AU; since the average distance for Pluto from the Sun is 39.3 AU then the distance is nearly twice.
What is the leading hypothesis for the Moon's formation? What evidence supports this hypothesis?
A giant impact between Earth and a large planetismal which broke off a part of Earth. Two pieces of evidence support this. The composition of the Moon and the existence of easily vaporized ingredients than Earth.
What is an ellipse? define its foci, semimajor axis and eccentricity
A special type of oval. A foci is two points equal position inside of the oval, semi-major axis is a vertical line drawn the long side of the oval, eccentricity is how squashed the circle is
Define momentum and force. What do we mean when we say that momentum can be changed only by a net force?
An object travelling with velocity has momentum (p) which is equal to the product of mass (m) of object and its velocity (v) p=mv. Force (F) is defined as the acceleration (a) times the mass (m) of an object (rate of change of momentum) F=ma. Momentum can be changed only if the velocity of the object gets changed. Rate of change is velocity is acceleration. Acceleration can be produced only if a force acts on the object. Therefore, momentum can be changed only by a net force.
Define speed, velocity, and acceleration. What are the units of acceleration? What is the acceleration of gravity?
An object travels a distance in unit time is known as speed. An object displaces in unit time is known as velocity. The change in the velocity of an object in unit time is known as acceleration. m/s^2. Under the influence of Earth's gravity, every object tends to fall on the surface of Earth with same acceleration.
What are asteroids and comets, how did they come to exist? How and why are they different?
Asteroids are leftovers in formation of inner solar planets while comets are leftovers in the formation of outer solar planets. Asteroids are rocky and comets are icy.
Describe the laws of conservation of angular momentum and conservation of energy. Give an example of how each is important in astronomy.
CAM pertains to the fact that an object's angular momentum will not change unless there is a transfer of angular momentum from or to another object. One example is how the Earth continues to rotate while it traverses its orbital path around the sun. CE pertains to the fact that energy will not appear from thin air or rather disappear into nothing. One example is the exterior of planets can cool by releasing energy into space.
Make a summary of the major roles that Copernicus, Tycho, Kepler, and Galileo played in overturning the ancient belief in an Earth-centered universe
Copernicus predicted the positions of planets in the solar system and proposed the idea of a Sun-centered solar system. Tycho provided better observational data and collected data for positions of stars and planets in the sky. Kepler discovered that planetary orbits are elliptical but not circular and created three laws to explain this. Galileo built a telescope and observed a lot of stuff
How do the tides vary with the phase of the Moon? Why?
During the times of full and new moons, high tides will be more high and low tides will be more low. They are called spring high tides, they are strong when Earth, Sun and the Moon are along a line. During quarter phases of the Moon we observe very weak tides called neap tides. These occur to the gravitational forces of Moon and Sun are perpendicular to each other.
state and explain each of keplers laws
First law is each planet orbits around the Sun in an ellipse. Second law is the planet is faster in its orbit during part that is closer to the Sun and slower further away. Third law more distant planets orbit the Sun at slower speeds.
What was the Copernican revolution, and how did it change the human view of the universe?
He was convinced the Sun-centered idea must be correct. The revolution changed the human view of the universe fundamentally
Define kinetic energy, radiative energy, and potential energy, with at least two examples of each.
Kinetic energy is the energy of motion. A falling rock has a kinetic energy. A molecule that is moving in the air has kinetic energy. Radiative energy is energy carried by light. The sunlight warms the surface of Earth. Light can alter molecules in human eyes that is how we see. Potential energy is energy stored that can be later converted to kinetic energy and radiative energy. A rock perched on the edge has gravitational potential energy that will be converted to kinetic energy if it falls off the edge. Gasoline contains chemical potential energy that can be converted to a moving car's kinetic energy.
Briefly describe the layout of the solar system as it would appear from beyond the orbit of Neptune
Our solar system is a arrangement of planets that rotate around Sun in definite orbits. The solar system consists of two types of planets. 4 planets as one group are called terrestrial planets and the other 4 planets are called jovian planets. The solar system ends with Neptune one of the jovian planets and beyond the orbit of Neptune there exists dwarf planet like Pluto. Further out we find large number of objects in two groups Kuiper belt and Oort cloud. These contain small bodies like the solar system remnants and large number of icy bodies.
Briefly describe the four major structures of our solar system that provide clues to how it formed
Patterns of motion among large bodies. Eight planets are divided in to two groups. The presence of asteroids and comets between the orbits of planets. Exceptions to the rules.
What do we mean by the Ptolmaic model? How did this model account for the apparent retrograde motion of planets?
Ptolemy adapted and synthesized the earlier ideas into a single system that could predict planetary positions to a good accuracy. The explanation for retrograde motion was that each planet moves around Earth on a small circle that turns upon a larger
Define and distinguish temperature and thermal energy.
Temperature is the average kinetic energy of all atoms in a substance. Thermal energy is the total kinetic energy of various individual items like molecules and atoms that move randomly with some type of substance like with the gas of a star. Temperature increases with increase in thermal energy.
What are the basic differences between terrestrial and jovian planets?
Terrestial are typically rocky, small, and very near to the Sun. Jovian are large gas rich planets that orbit further away from the Sun.
Explain how the Moon creates tides on Earth. Why do we have two high and low tides each day?
The attractive gravitational force between Earth and the Moon affects different parts of Earth slightly. The strength of the gravitational force decline with distance. The difference in the attractive force creates the tidal force, which stretches Earth to create two tidal bulges. The rotation of Earth will carry each location through each of the two tidal bulges ones per day.
Use table 6.1, Notice the relationship between distance from the Sun and surface temperature. Describe the trend, why it exists, and any notable exceptions.
The relationship between distance and the Sun are inverse. As you move further away from the Sun the surface temperature of the planet decreases. One exception is if a planet has a strong atmosphere like Venus, which is way hotter than the closer planet Mercury.
Summarize the universal law of gravitation both in words and with an equation.
There exists an attractive force called gravity between every two masses. The gravitational force strength between a pair of masses is directly proportional to the product of their masses. The strength of the gravity is inversely proportional to the square of the distance between two masses. That is, increase in the distance between two masses decreases the gravitational force between the two masses. F=G(m1m2/d2) (F-gravitational force, G-gravitational constant of value 6.67x10^-11, m1m2- masses of the two objects, d-distance between the two masses)
Use table 6.1, Describe in general how the columns for density, composition, and distance support the classification of either terrestrial or jovian.
There is a huge drop off in density from terrestrial to jovian planets. The smaller terrestrial planets are composed mostly of rock which has more composition. Terrestrial planets are closer to the Sun.
Why did ancient peoples study astronomy? describe the origins of our day, week, month
They used astronomy to manage time, track the seasons and help them navigate. Day come from sunrise, months came from Moon's cycle, year came from change of seasons using astronomical indicators
Why was astronomy important to people in ancient times?
Through observing the sky, ancient people were aware of date and time with having calendar. Due to their insufficient equipment many myths also came from observing the sky.
Use table 6.1, Which planets would you expect to not have seasons?
Venus would not have seasons because it is the only planet that is not tilted on a axis.
You and Earth attract each other gravitationally, so you should also be subject to a tidal force resulting from the difference between the gravitational attraction felt by your feet and that felt by your head. Explain why you can't feel this tidal force.
We do experience this tidal force, but due to our small mass in comparison with Earth's surface, the tidal force is so small we can not detect it.
Use table 6.1, Describe the trend you see in orbital periods and explain the trend in terms of Kepler's third law.
p^2=a^3
What is mass-energy? Explain the formula E=mc^2
the second most important form of potential energy in the energy in the mass itself. Einstein created this formula to express the idea that mass can be converted to other form of energy. E is the amount of potential energy and c is the speed of light.
