PHYS 103 Astronomy Exam 2 (Chapter 5-8)
The number of moons of Mercury is
0
The number of moons of Venus is
0
An ion rocket engine produces 1 Newton of thrust. What acceleration can it give to a space probe with a mass of 1000kg?
0.001 m/s².
An ion rocket engine produces 50 Newtons of thrust. What acceleration can it give to a space probe with a mass of 10,000kg?
0.005 m/s².
The angle between the rotation axis of a planet and the perpendicular to the plane of its orbit is called its "axial tilt." The axial tilt of Mercury is
0.01 degrees.
What total force will cause an object with a mass of 2kg to gain 5 meters per second every second?
10 Newtons.
Suppose that you try to lift an object by exerting an upward force of 5 Newtons on it. If gravity exerts a force of 20 Newtons downward on the object, what is the total force on the object?
15 Newtons downward.
Suppose that you lift an object by exerting an upward force of 12 Newtons on it. If gravity exerts a force of 10 Newtons downward on the object, what is the total force on the object?
2 Newtons.
The number of moons of Mars is
2.
What total force will cause an object with a mass of 0.5kg to gain 100 meters per second every second?
50 Newtons.
What total force will cause an object with a mass of 10kg to gain 5 meters per second every second?
50 Newtons.
The density of water is 1000kg/m³ while the density of iron is 7800kg/m³. Which of the following values is a plausible value for the density of a terrestrial planet?
5000kg/m³
The density of water is 1000kg/m³, the density of rock is about 3000kg/m³, and the density of iron is 7800kg/m³. Which of the following densities is closest to the average density of the Earth?
5200kg/m³
If the planets are numbered from 1 to 8, going outward from the Sun, the planet Uranus is number
7.
The density of water is 1000kg/m³ while the density of rock is 3000kg/m³. Which of the following values is a plausible value for the density of a Jovian planet?
700kg/m³
Call the time it takes Venus to orbit the Sun a "Venusian year." Call the time it takes Venus to rotate once on its axis relative to the distant stars a "Venusian sidereal day." Which of the following statements about these two time periods is true?
A Venusian year is shorter than a Venusian sidereal day.
The first human landing on the Moon was
Apollo 11 in 1969.
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance and one object is twice as heavy. Who predicted that the heavier object would hit the ground long before the lighter one?
Aristotle.
Which of the following types of objects include things that could reasonably be described as "flying rocks" or, for the larger ones, "flying mountains?"
Asteroids.
Which of the following objects has no magnetic field at all?
Earth's Moon
Galileo predicted that dropping a wooden ball and an iron ball at exactly the same time would result in them hitting the ground at the same time, so long as air friction was negligible. When he actually did the experiment, the balls hit the ground very close together, but sometimes the wooden ball hit first and sometimes the iron one hit first. If we repeat his experiment today, we find exactly the same thing. Which of the following conclusions is appropriate?
Galileo really did the experiment.
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance and one object is twice as heavy. Who predicted that both objects would hit the ground at the same time?
Galileo.
Who discovered Newton's First Law of Motion?
Galileo.
The Apollo program was thought to be part of a "race to the Moon" with the Soviet Union. Actually
It was a close race. The Soviets actually built a Moon rocket and tested it.
Which of the following types of object could reasonably be described as "dirty snowballs" or, for the larger ones, "flying icebergs?"
Kuiper Belt Objects.
Which of the following objects has no overall magnetic field except for small regions due to magnetized ore deposits?
Mars
Which of the following planets has just two moons?
Mars
Which of the following planets or moons has an atmosphere with about 1% of the surface pressure of Earth's?
Mars
Which of these planets has a solar day that is very close to an Earth day in length?
Mars
Which of these planets is the farthest from the Sun? a Mars b Mercury c Venus d Earth
Mars
The Asteroid Belt is between the orbits of
Mars and Jupiter.
Which of these sequences places the inner planets in the correct order from the Sun, from the closest to the farthest?
Mercury, Venus, Earth, Mars (farthest)
The angle between the rotation axis of a planet and the perpendicular to the plane of its orbit is called its "axial tilt." Which of these planets has an axial tilt that is less than one degree?
Mercury.
Which of these planets is the farthest from the Sun? a Jupiter b Saturn c Neptune d Uranus e Mars
Neptune
The first space probe to place a robotic rover on the surface of Mars was
Pathfinder.
The first space probe to test the air-bag landing system was
Pathfinder.
Which of these Moons rises in the West as seen from its primary planet?
Phobos
The first space probes to land on another planet were from the
Russian Venera series.
A rocket is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that it is desired to lower it to a new circular orbit, sliightly closer to the surface. The rocket flips over and fires its main rocket engine in a short burst to slow its speed to 4.96 miles per second. What must it do next?
Slow its speed again by a bit when its distance from the Earth stops decreasing.
The first successful soft landing on the Moon was
Surveyor 1 in 1966.
When Newton calculated the magnitude of the acceleration of Earth's Moon, and compared it to the acceleration of falling objects on the surface of the Earth, he found that
The Moon's acceleration was smaller.
Why couldn't we just fly a Space Shuttle to the Moon for at least a fly-by?
The Space Shuttle did not have enough fuel to reach escape velocity.
Why don't we just shoot all of our really nasty waste products into the Sun where they could not possibly bother anyone?
The Sun is actually the hardest part of the Solar System to get to from here.
The capture theory, in which our Moon forms separately and is captured by the Earth,became popular when computer models showed that such a capture would have been possible.
The capture theory was dropped because it predicts that the Moon should have hydrated rocks and it does not.
A book, weighing 10 Newtons, sits on a table. Which of the following pairs of forces is an action-reaction pair?
The force that the book exerts on the table and the force that the table exerts on the book.
You are standing in an elevator that is accelerating upward at 1m/s². Which of the following pairs of forces is an action-reaction pair that have to be exactly equal and opposite to each other?
The force that the floor of the elevator exerts on you and the force that you exert on the floor of the elevator.
Which of the following circumstances would suggest that a rotating planet contains a core of liquid iron?
The planet is much denser than rock and has a magnetic field.
Which of the following statements about the moons of terrestrial planets is currently accepted?
They sometimes capture moons by accident.
An atmosphere with about 90 times the surface pressure of Earth's is found on the surface of.
Venus
Which of the following three systems is regarded as the most normal for a terrestrial planet?
Venus, with no moons at all.
The first soft landing on Mars was by the
Viking landers.
A lunar crater is best described as
a circular ring wall surrounding a flat area.
The ancient Greeks had difficulty accounting for the motion of a thrown object because they thought that
a force was needed to keep the object moving.
The magnetic field of Mercury is
about 1% of the Earth's magnetic field.
Mercury has
almost no atmosphere.
In comparison to Kepler's Laws of Planetary Motion, Newton's theory of Universal Gravitation predicted
almost the same motions but with corrections.
Mars has
an atmosphere of carbon dioxide with about 1% the surface pressure of Earth's.
Venus has
an atmosphere of carbon dioxide with about 90 times the surface pressure of Earth's.
Once its rockets have ceased firing, an Intercontinental Ballistic Missile will follow a path that is best described as
an ellipse with the center of the Earth at one focus.
So long as air resistance can be neglected, the most accurate description of the path taken by an artillery shell is
an ellipse with the center of the Earth at one focus.
Current theory says that the Moon formed when
another planet collided with the Earth.
Kepler's Laws
are explained by a force that attracts each planet to the Sun.
Our Sun sends out intense streams of charged particle radiation. Most of these charged particles
are trapped by the Earth's magnetic field for a while and then strike the atmosphere over the poles.
In the present surface environment of Mars, water has been confirmed to exist
as short-lived spurts of liquid water.
On Earth, you might find a temperature of 59°F on a Spring or Fall day in the temperate zone. On Mars, you might expect that temperature
at noon near the equator.
For a planet to have substantial amounts of liquid water on its surface, it must have
atmospheric pressure above the triple point of water.
Asteroids are usually found in the asteroid belt, which is
between the orbits of Mars and Jupiter.
Galileo's approach to understanding moving objects was to
build things that he could measure.
At present (within the last few hundred years), the distance from Mars to the Sun
changes enough to make the intensity of sunlight vary by 40 percent.
Milankovich cycles refer to
changes in the intensity of sunlight due to shifts in both the Earth's orbit and rotation axis.
The currently accepted theory of how the Moon formed is the
collision theory.
When a space probe uses a gravitational slingshot maneuver, it
comes close to a planet to change the probe's speed and direction.
The impacts of large objects on the surface of the Moon have caused
craters.
Apollo 8 made the first
crewed orbit of the Moon.
Mars' orbit is currently (within the last few hundred years)
elliptical enough to make the intensity of sunlight vary by 40 percent.
Comets usually follow orbits which are
elliptical with aphelia far outside the orbit of Mars.
The magnetic field of Earth's Moon is
essentially zero.
The magnetic field of Mars is
essentially zero.
The magnetic field of Venus is
essentially zero.
Earth's orbit is currently elliptical enough to make the intensity of sunlight vary by 6 percent. The shortest Earth-Sun distance (and highest intensity sunlight) currently occurs
every January.
The International Space Station (ISS) is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose that a rocket pushes it and quickly increases its speed to 6 miles per second. The ISS will then
follow an ellipse that rises and then descends again.
Freely falling objects with different masses fall with the same acceleration because
gravity exerts more force on the more massive object.
Mars
has a solar day that is very close to an Earth day in length.
Mercury rotates so that it
has a solar day that last for two complete orbits around the Sun.
The Curiosity Mars rover
has been operating on Mars for eight years so far (as of 2020).
The force of gravity explains
how the tides work but not how lightning works.
The statement that lunar material is much "dryer" than Earth material refers to the absence of
hydrated minerals.
Comets are usually made of
ice and possibly frozen gas.
Kuiper Belt objects are usually made of
ice and possibly frozen gas.
The circular structures on the surface of the Moon are the result of
impacts.
The presence of frozen water on Venus is
impossible because every part of it is too hot for water ice.
A model in which the Moon forms from the same rotating cloud of gas and dust as the Earth would predict that the Moon's orbit should be
in the plane of the Earth's equator.
The Earth's Moon
is 1/4 the size of the Earth, which is unusually large for a moon.
If the acceleration of an object is zero, its speed
is not changing.
According to Newton's Law of Gravity, the gravitational attraction of the Earth for other objects, such as the Moon, apples on trees and space shuttles in low earth orbit,
is smaller for objects farther from the Earth but never vanishes entirely.
According to Newton's Law of Gravity, the gravitational attraction of the Earth for other objects, such as the Moon, apples on trees and spacecraft in low earth orbit,
is smaller for objects farther from the Earth but never vanishes entirely.
The Moon's orbit
is somewhat tilted relative to the plane of the Earth's equator.
The Law of Inertia says that if an object is not acted on by any outside force,
its acceleration will be zero.
Galileo said that a moving object with nothing pushing or pulling on it will always
keep moving at the same speed.
The Law of Inertia states that a moving object will
keep moving if no force acts on it.
A unit of mass is the
kilogram.
The Jovian planets typically have
large systems of moons.
The number of maria on the side of the Moon facing away from the Earth is
less than on the side facing Earth.
Compared to the rest of the Lunar surface, the Lunar Maria are
lower and younger.
The Surveyor series of spacecraft
made unmanned landings on the Moon in the 1960s.
Ancient lava flows on the Moon are called Lunar
maria.
In the surface environment of Mars, water exists
mostly as ice and water vapor.
Galileo said that once an object is set in motion, it will keep moving at the same speed so long as
no force is acting on it.
When an arrow is fired from a bow, the arrow keeps moving after it leaves the bow because
no force stops it.
The observed magnetic field of Mercury is surprising because it was expected to have
no magnetic field at all because it rotates so slowly.
It is expected that a normal terrestrial planet, with no accidental encounters that could add or subtract moons, should have
no moon.
The Moon rotates on its axis relative to the distant stars
once every sidereal month.
The distance from the Earth to the Sun is
one astronomical unit.
The Opportunity Mars rover
operated on Mars for fifteen years.
The presence of frozen water on Mercury is
possible because it has almost no axial tilt so that its poles never directly face the Sun.
The Earth's magnetic field plays an essential role in
protecting the Earth from charged particles from the Sun.
Space probes often visit several planets before getting to their final destinations. The main reason they do this is to
reduce the amount of rocket fuel needed.
Asteroids can be made of
rock and possibly iron.
Venus
rotates backwards so that the Sun rises in the West.
The current model for the way that planets acquire magnetic fields requires which of the following combinations of things?
rotation and a core that contains a liquid electrical conductor.
Aristotle said that a moving earthly or `mundane' object with nothing pushing or pulling on it will always
slow down and stop.
When Galileo dropped a wooden ball and a heavier iron ball at the same time, he found that
sometimes the wooden ball hit first, sometimes the iron one hit first.
Since the last Apollo mission to the Moon and the last Soviet LUNA sample-return mission
spacecraft began to be sent there again by 1994.
Aristotle said that the amount of force on a moving earthly object determines its
speed.
Which of these is a distinctive feature of the Earth's atmosphere?
temperature and pressure permit all three forms of water.
An artificial satellite such as the International Space Station stays up because
the Earth curves out from under it as fast as it falls.
In Kepler's Laws of planetary motion the Earth moves around a Sun that is fixed in space. In Newton's theory,
the Sun and Earth move around a common center of mass.
In Newton's Theory of planetary motion,
the Sun and Earth move around each other.
An astronomical unit is defined to be
the average distance from the Earth to the Sun.
The force that acts on a rocket because its engine is firing is exerted by
the exhaust from the rocket.
Suppose that you drop two objects from the same height at the same time. Both objects are heavy enough to be unaffected by air resistance. If one object is twice as heavy as the other, Aristotle would predict that
the heavier object would hit the ground long before the lighter one.
If you are told that a 20 kilogram object is raised by 10 meters, you know that
the mass of the object is 20 kilograms.
One way to change the course of an asteroid is to place a `mass driver' on it. The mass driver is really just a catapult that throws things (like rocks for example) away from the asteroid. The force that acts on the combined object (mass driver plus asteroid) is actually exerted by
the rocks that the catapult throws.
Suppose that an object with a mass of one kilogram and an object with a mass of two kilograms are both in free fall near the Earth's surface. As compared to the one kilogram object, the two kilogram object accelerates
the same because gravity pulls on it more strongly and it has more inertia.
The Moon rotates on its axis so that it always keeps
the same side (its far side) pointed away from the Earth.
Moon missions since 2007 have mostly been focused on
the search for water needed for a Moon base.
In the ancient Greek theory of gravity, everything was attracted to the center of the universe. In Newton's theory of gravity, everything was attracted
to every other object in the universe.
When Newton calculated the magnitude and direction of the acceleration of Earth's Moon, he found that the direction was
toward the Earth.
When Newton calculated the magnitude and direction of the acceleration for a planet that was following Kepler's Laws, he found that the direction of the acceleration was
toward the Sun.
Mercury rotates so that its sidereal day lasts for
two thirds of a complete orbit around the Sun.
The distance from the Earth to the Moon
varies enough that sometimes we get an annular solar eclipse.
At present (within the last few hundred years) the orbit of Mars around the Sun is
very elliptical so that.the intensity of sunlight varies by 40 percent.
A comet that is passing close to the Sun will have a tail that is most likely
very long because sunlight is pushing on it.
The Law of Inertia says that if an object is not acted on by any outside force, its acceleration
will always be zero.
