astronomy chapters 5-8 lecture & chapter questions
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.
An ion rocket engine produces 100 Newtons of thrust. What acceleration can it give to a space probe with a mass of 10,000kg?
0.01 m/s².
The average radius of the Earth's orbit is
1au
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 would indicate an object that might consist of rock surrounding an iron core?
4000kg/m³
The first human landing on the Moon was
Apollo 11 in 1969.
Which of these Mars rovers has been operating on the surface of Mars for six years so far (as of 2018).
Curiosity
Newton's Second Law
F=ma if a total force F on an object produces an amount of acceleration a, then these quantities are related
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 it is desired to raise it to a new circular orbit, farther from the surface by having a rocket give it one or more short boosts. Which of the following schemes will work?
Increase its speed to 6 miles per second to put it on a rising path and give it another speed boost when its distance from the Earth stops increasing.
Changes in the intensity of sunlight due to shifts in both the Earth's orbit and rotation axis cause
Milankovich cycles.
Which of these Mars rovers has been operating on the surface of Mars for fourteen years so far (as of 2018)?
Opportunity
Compare the magnitude of the acceleration of Earth's Moon to the acceleration of falling objects on the surface of the Earth.
The Moon's acceleration is 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.
A horse is pulling a cart along a road. Which of the following pairs of forces is an action-reaction pair
The force of horse on the road and the force of the road on the horse.
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 has 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.
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 surface magnetic field of Mercury is
about 1% of the Earth's magnetic field.
The atmospheric pressure on the surface of Mars is
about 1% the surface pressure of Earth's atmosphere.
So far (as of 2008), the planet Venus has been visited by
about 20 successful space probes.
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.
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, Galileo predicted that
both objects would hit the ground at the same time.
Most Kuiper Belt Objects are similar in composition to
comets
The discovery that there is water ice on the Moon has motivated many nations to launch Moon missions because it
could make a Moon base possible.
The dark side of the Moon, where the Sun never shines,
does not exist.
The magnetic field of Venus is
essentially zero
A rocket that leaves the Earth's atmosphere at a speed of 4 miles per second will
follow an elliptical path that is partly below the surface of the Earth.
The Opportunity Mars rover
has been operating on Mars for fourteen years so far (as of 2018)
The side of the Moon that faces away from the Earth
has only a few small lunar maria.
The current model for the way that planets acquire magnetic fields suggests that a rapidly rotating planet will
have a magnetic field if its core contains enough liquid electrical conductor.
Kuiper Belt objects are usually made of
ice and possibly frozen gas
Newton's Third Law
if object A exerts a force on object B, object B exerts an equal and opposite force back on object A
Newton's addition law
if two forces act on one object, the product of both forces added together are the total force If both forces are acting in opposite directions then they're subtracted If they go in the same direction then they're added
The circular structures on the surface of the Moon are the result of
impacts.
A model in which the Moon forms by breaking away from the Earth would predict that the Moon's orbit should be
in the plane of the Earth's equator.
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.
The gravitational attraction of the Earth for other objects,
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
Mercury rotates so that, relative to the Sun
it rotates just once during two complete orbits around the Sun.
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.
The atmospheric pressure at the surface of Venus is
many times the pressure at the surface of the Earth.
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 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 magnetic field of Mars is
present only locally, near magnetized ore deposits.
The phase diagram for water is presented on a graph with axes for temperature and
pressure.
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.
An artificial satellite such as the International Space Station stays up because
the Earth curves out from under it as fast as it falls; it falls below a straight-line path in exactly the same way that the curved surface of the Earth does.
The capture theory, in which the Moon forms as a separate object similar to Earth and is then captured by the Earth, would predict that
the Moon should have an iron core similar to Earth's.
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.
The recoil or 'kick' of a gun that is firing a bullet is a force exerted on the gun by
the bullet
In comparison to Kepler's Laws of Planetary Motion, Newton's theory of Universal Gravitation predicted almost the same motions, but with small corrections due to
the gravitational attractions between different planets.
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.
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 twice as strongly and it has twice the inertia.
Moon missions since 2007 have mostly been focused on
the search for water needed for a Moon base.
In Newton's theory of gravity, everything is attracted
to every other object in the universe.
Pathfinder was the first
to use airbags to land on Mars.
The acceleration of Earth's Moon is
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.
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 planet whose atmospheric pressure is exactly at the triple point of water and whose surface temperature has a range that includes the triple point will have
water as ice or vapor, depending on the temperature.
Newton's First Law
when total force acting on an object is zero, then its acceleration is also zero
The Van Allen Belts are
where Earth's magnetic field traps charged particles from the Sun.
Which of the following temperatures would be most likely at noon on the hottest day of the year in the warmest part of Mars?
50F.
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.
Sub-orbital flight
an object near the earth's surface traveling at less than 5 miles per second follows the earth
Hydrated minerals on the Moon
are almost completely absent.
Venus's rotation
rotates backwards so that the Sun rises in the West.
As viewed from the star Polaris, Venus
rotates clockwise and goes around the Sun counter-clockwise.
Apollo 11 made the first
crewed landing on the Moon.
What total force will cause an object with a mass of 5kg to gain 10 meters per second every second?
50 Newtons
It is currently thought that moons typically form near
Jovian planets such as Jupiter and Saturn.
Which of the following planets has a moon that rises in the West?
Mars
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.
Since 1990, the major spacefaring nations, Europe, China, Russia, Japan, India, and the U.S., have begun to return to the Moon. As of 2009, of these six space programs,
all except Russia have sent probes or orbiters to the Moon.
Kepler's Laws of planetary motion were originally obtained by fitting accurate observations. Newton explained those laws by a force that acts on each planet. The force that specifically explains Keplers Laws
attracts each planet to the Sun.
When Galileo wanted to understand how falling objects move, he did all of the things on the following list. Choose the one thing that is very different from the way that the ancient greeks approached the subject. He
built inclined planes and measured how balls roll down them.
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.
Temperatures on the surface of Mercury are
extremely varied because it has no atmosphere to spread the heat.
The Moon's orbit around the Earth
is elliptical enough to give us an annular solar eclipse when the Moon is near its apogee.
If the acceleration of an object is zero, its speed
is not changing
ed magnetic field of Mercury is surprising because it was expected to have
no magnetic field at all because it rotates so slowly.
Suppose that a comet is spotted while it is still far from the Sun (beyond the orbit of Mars). The tail of this comet is most likely
not yet formed.
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.
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.
A full cycle of day and night on Mars is called a `sol.' In terms of 24 hour Earth days, a Martian sol is
slightly longer than one Earth day.
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.
The Soviet Union had a secret program to put the first human on the Moon. This program
test launched their Moon Rocket several times, but it blew up each time.
Between the orbits of Mars and Jupiter you find
the Asteroid Belt.
If an object is moving at constant speed in a straight line, its acceleration is
the change in the object's speed divided by the time it takes.
According to Galileo, a thrown spear keeps moving after it has left the spear thrower's hand because
the force of friction with the air is not enough to stop the spear.
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.
A planet that is following Kepler's Laws, accelerates
towards the sun
Mercury rotates so that its sidereal day lasts for
two thirds of a complete orbit around the Sun.
According to our current model of how magnetic fields arise, the magnetic field of Earth's Moon is
understandable since the Moon rotates slowly and probably has no iron core.
The Law of Inertia says that if an object is not acted on by any outside force, its acceleration
will always be zero.