Astronomy Exam 2

A solar sail is a large sheet of light-reflecting plastic spread on an extremely low-mass framework and attached to a spacecraft. Sunlight exerts a force on the sail and moves the spacecraft. Suppose the spacecraft has a total mass of 5000kg (including the sail) and sunlight exerts a total force of 5N on the sail. What will be the acceleration of the spacecraft?

0.001m/s².

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.

The first successful soft landing on the Moon was Surveyor 1 in

1966.

If the planets are numbered from 1 to 8, going outward from the Sun, the planet Mars is number

4.

What total force will cause an object with a mass of 50kg to gain 1 meter per second every second?

50 Newtons.

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

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.

Which of the following planets has a moon that rises in the West?

Mars

Which of these planets has a solar day that is very close to an Earth day in length?

Mars

Which of the following planets can be said to have almost no atmosphere?

Mercury

Which of these Mars rovers has been operating on the surface of Mars for fourteen years so far (as of 2018)?

Opportunity

The first space probe to place a robotic rover on the surface of Mars was

Pathfinder.

The first space probes to land on another planet were from the

Russian Venera series.

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.

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.

Water ice can be found on all but one of these planets. Which one has no ice?

Venus

Which of the following planets has no magnetic field of any kind?

Venus

The ancient greeks thought that

a heavy object should fall faster than a lighter object because the heavy object is pulled down with more force.

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.

For a planet to have substantial amounts of liquid water on its surface, it must have

atmospheric pressure above the triple point of water.

Space probes often use gravitational slingshot maneuvers. The main purpose of these maneuvers is to

change the direction and speed of the probe without using rockets.

Which of the following objects would be most likely to have a long elliptical orbit that takes it from far outside the orbit of Mars to a close approach to the Sun?

comet.

The magnetic field of Mars is

essentially zero.

Suppose that a spacecraft is in a roughly circular orbit near the surface of the Earth, moving at around 5 miles per second. Suppose the spacecraft flips over backwards and fires its rocket engine to slow its speed to 4.96 miles per second. The spacecraft will then

follow an ellipse that descends a bit and then rises again.

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.

The circular structures on the surface of the Moon are the result of

impacts.

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.

The Moon's orbit around the Earth

is elliptical enough to give us an annular solar eclipse when the Moon is near its apogee.

The gravitational attraction of the Earth for other objects,

is smaller for objects farther from the Earth but never vanishes entirely.

The Law of Inertia states that a moving object will

keep moving if no force acts on it.

The Lunar Maria are thought to have been caused by ancient

lava flows from large impacts.

It is expected that a normal terrestrial planet, with no accidental encounters that could add or subtract moons, should have

no moon.

The phase diagram for water is presented on a graph with axes for temperature and

pressure.

The Earth's magnetic field plays an essential role in

protecting the Earth from charged particles from the Sun.

As viewed from the star Polaris, Venus

rotates clockwise and goes around the Sun counter-clockwise.

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.

At present (within the last few hundred years) the orbit of the Earth around the Sun is

slightly elliptical so that.the intensity of sunlight varies by 6 percent.

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.

When Newton calculated the magnitude of the acceleration of Earth's Moon relative to the Earth, and compared it to the acceleration of falling objects on the surface of the Earth, he found that

the Moon's acceleration was smaller.

An astronomical unit is defined to be

the average distance from the Earth to the Sun.

For an object that is moving along a straight path, the acceleration is

the change in the object's speed divided by the time it takes.

If you are told that an object that weighs 20 Newtons is raised a distance of 10 meters, you know that.

the force of gravity on the object is 20 Newtons.

The Moon rotates on its axis so that it always keeps

the same side (its far side) pointed away from the Earth.

Mercury rotates so that its sidereal day lasts for

two thirds of a complete orbit around the Sun.

Apollo 11 made the first

crewed landing on the Moon.

The currently accepted theory of how the Moon formed is the

collision theory.