ast 103 - test 1

Question 1

Roughly how many stars are in the Milky Way Galaxy?

Answer 1

100 billion

Question 2

Approximately how fast are you moving with the rotation of Earth?

Answer 2

1,300 km/hr

Question 3

How long does it take our solar system to complete one orbit around the Milky Way Galaxy?

Answer 3

230 million years

Question 4

Which scientists played a major role in overturning the ancient idea of an Earth-centered universe, and about when?

Answer 4

Copernicus, Kepler, and Galileo; about 400 years ago

Question 5

Earth is made mostly of metals and rocks. Where did this material come from?

Answer 5

it was produced by nuclear fusion in the stars

Question 6

What is the ecliptic?

Answer 6

the Sun’s apparent path along the celestial sphere

Question 7

Momentum is defined as

Answer 7

mass times velocity

Question 8

Kepler’s third law, p^2 = a^3, means that:
A) a planet’s period does not depend on the eccentricity of its orbit
B) all orbits with the same semimajor axis have the same period
C) the period of a planet does not depend on its mass
D) planets that are farther from the Sun move at slower average speeds than nearer planets

Answer 8

all of the above are correct.

Question 9

Why do we have seasons on Earth?

Answer 9

as Earth goes around the Sun and Earth’s axis remains pointed toward Polaris, the Northern and Southern hemispheres alternately receive more and less direct sunlight

Question 10

When are eclipse seasons?

Answer 10

when the nodes of the Moon’s orbit are nearly aligned with the Sun

Question 11

According to the universal law of gravitation, the force due to gravity is

Answer 11

inversely proportional to the square of the distance between objects

Question 12

According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will

Answer 12

increase by a factor of 4

Question 13

The names of the seven days of the week are based on the

Answer 13

most popular Norse gods

Question 14

Which of the following statements about scientific models is true?

Answer 14

a model can be used to explain and predict real phenomena

Question 15

Considering Einstein’s famous equation, E = mc^2, which of the following statements is true?

Answer 15

a small amount of mass can be turned into a large amount of energy

Question 16

How did the Ptolemaic model explain the apparent retrograde motion of the planets?

Answer 16

it held that the planets moved along small circles that moved on larger circles around Earth

Question 17

Kepler’s second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that

Answer 17

a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun

Question 18

What do scientists mean by verifiable observations?

Answer 18

statements that a person can, in principle, verify for themself

Question 19

Suppose an object is moving in a straight line at 50 miles/hr. According to Newton’s first law of motion, the object will

Answer 19

continue to move in the same way until it is acted upon by a force

Question 20

Newton’s second law of motion tells us that the net force applied to an object equals its

Answer 20

mass times acceleration

Question 21

Changing the orbit of a spacecraft by firing thrusters is an example of

Answer 21

Newton’s third law of motion

Question 22

Which of the following best describes the origin of ocean tides on Earth?

Answer 22

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth

Question 23

Which of the following statements about circumpolar stars is true at all latitudes?

Answer 23

they always remain above your horizon

Question 24

What is stellar parallax?

Answer 24

it is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth’s orbit of the Sun

Question 25

When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not?

Answer 25

Copernicus used perfect circles for the orbits of the planets

Question 26

From Kepler’s third law, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to

Answer 26

4 astronomical units

Question 27

In which of the following cases would you feel weightless?

Answer 27

while falling from a roof

Question 28

What is meant by a hypothesis?

Answer 28

an explanation for a phenomenon that makes a prediction

Question 29

The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them

Answer 29

weakens by a factor of 4

Question 30

The allowed shapes for orbits under the force of gravity are

Answer 30

ellipses, parabolas, and hyperbolas

Question 31

Imagine we’ve discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet?

Answer 31

It is less massive than Earth

Question 32

In addition to the conditions required for any solar eclipse, what must also be true in order for you to observe a total solar eclipse?

Answer 32

The Moon’s umbra must touch the area where you are located

Question 33

Suppose you heat up an oven and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven?

Answer 33

The water has a higher heat content than the oven

Question 34

What makes the North Star, Polaris, special?

Answer 34

It appears very near the north celestial pole.

Question 35

What is an astronomical unit?

Answer 35

the average distance from Earth to the Sun

Question 36

The center of mass of a binary star system is

Answer 36

the point at which the two objects would balance if they were somehow connected

Question 37

The fact that the Voyager spacecraft continue to speed out of the solar system, even though its rockets have no fuel, is an example of

Answer 37

Newton’s first law of motion

Question 38

We can’t detect stellar parallax with naked- eye observations. Which of the following would make parallax easier to observe?

Answer 38

increasing the size of Earth’s orbit

Question 39

Suppose that two objects collide. Which of the following things is not the same both before and after the collision?

Answer 39

the total temperature of the objects

Question 40

Which of the following is smallest?

Answer 40

size of a typical planet