Question 1

Tycho demonstrated that the supernova of 1572 was far from Earth by showing that

Accepted Answer

A)  the object was moving in our direction. 
B)  it did not appear to move against the background of the stars. 
C)  its spectrum was shifted to the red. 
D)  it disappeared behind the Sun.

Question 2

What path would a planet (like Earth) take if the force of gravity from the Sun were to be suddenly removed?

Accepted Answer

A)  The planet would move in a straight line tangential to its present orbit. 
B)  The planet would stop moving altogether because there would be no gravity acting on it. 
C)  The planet would move in a straight line outward, directly away from the Sun's position. 
D)  The planet would begin to move in a long ellipse with the Sun at one focus.

Question 3

How was the planet Neptune discovered?

Accepted Answer

A)  Neptune was discovered by mathematical prediction using Newton's laws. 
B)  Neptune happened to pass close to Jupiter in the sky and was discovered by an astronomer studying Jupiter. 
C)  Neptune was discovered accidentally during a telescopic survey of the sky. 
D)  No one knows-Neptune has been known since ancient times.

Question 4

Which of these astronomers was one of the first to use a telescope for viewing the sky?

Accepted Answer

A)  Ptolemy 
B)  Newton 
C)  Brahe 
D)  Galileo

Question 5

The BEST time(s) to see inferior planets from Earth is (are) when these planets are at positions of

Accepted Answer

A)  opposition. 
B)  greatest elongation. 
C)  inferior conjunction. 
D)  superior conjunction.

Question 6

What is the linear momentum, p, of an object?

Accepted Answer

A)  object's mass divided by its velocity, p = m/v 
B)  product of the object's moment of inertia and its rotational speed, p = I$ \omega $ 
C)  half the product of the object's mass times the square of its speed, p = 1/2 mv2 
D)  product of the object's mass times its velocity, p = mv

Question 7

A planet at inferior conjunction is always

Accepted Answer

A)  on the opposite side of the sky from the Sun as seen from Earth. 
B)  closer to Earth than the Sun is. 
C)  below Earth's horizon and therefore invisible. 
D)  farther away from Earth than the Sun is.

Question 8

To specify an object's velocity, one needs to specify

Accepted Answer

A)  how fast it is moving and also its mass. 
B)  only how fast it is moving. 
C)  only in which direction it is moving. 
D)  how fast it is moving and also in which direction it is moving.

Question 9

In Ptolemy's description of the solar system, the deferent is a(n)

Accepted Answer

A)  elliptical path along which a planet moves around the Sun. 
B)  circular path (around the Sun) along which the center of a planet's epicycle moves. 
C)  circular path (around Earth) along which the center of a planet's epicycle moves. 
D)  circular path along which a planet moves while the center of the path moves in a circle around Earth.

Question 10

What is the angle between the line from Earth to Mercury and the line from Mercury to the Sun when Mercury is at greatest elongation?

Accepted Answer

A)  90° 
B)  180° 
C)  anywhere between 0° and 180°, depending on the particular planetary alignment 
D)  0°

Question 11

Suppose two asteroids are located at the same distance from the Sun. One asteroid has twice the mass of the other. According to Newton's law of gravitation (and ignoring all forces except that from the Sun),

Accepted Answer

A)  the more massive asteroid feels half the force that the other does. 
B)  the more massive asteroid feels twice the force that the other does. 
C)  neither feels any force because they are weightless in space. 
D)  both asteroids feel the same force because gravity acts equally on all objects.

Question 12

In the geocentric model of the solar system developed by Ptolemy, the planets move

Accepted Answer

A)  with varying speeds in elliptical orbits around Earth. 
B)  at constant speeds in circular orbits around Earth. 
C)  in circular epicycles around the Sun, while the Sun moves in a circular orbit around Earth. 
D)  in circular epicycles, while the centers of the epicycles move in circular orbits around Earth.

Question 13

The angle of greatest elongation of Saturn (the greatest value of the angle between the Earth-Sun line and the Earth-Saturn line) is

Accepted Answer

A)  46$\degree$ 
B)  90$\degree$ 
C)  120$\degree$ 
D)  180$\degree$

Question 14

As far as is known, the first person who claimed that natural phenomena could be described by mathematics was

Accepted Answer

A)  Copernicus. 
B)  Pythagoras. 
C)  Aristotle. 
D)  Ptolemy.

Question 15

Which of these objects could transit (pass in front of) the Sun as seen from Saturn?

Accepted Answer

A)  Uranus 
B)  Neptune 
C)  Pluto 
D)  Jupiter

Question 16

If an astronaut were to look back from his spacecraft toward the solar system and measure that the angle between Earth and the Sun was 1 arcsecond, how far from the un would the astronaut be? (Assume that the Earth-Sun line is at right angles to your line of sight.)

Accepted Answer

A)  1 Mpc 
B)  1 au 
C)  1 pc 
D)  1 ly

Question 17

The discovery of gravitational radiation is an unusual example of the scientific method because

Accepted Answer

A)  it began with observations made over a century ago. 
B)  it began with theoretical calculations rather than observations. 
C)  the observations that began the investigation completely disproved the currently accepted model, thus leaving the theorists with no structure to build on. 
D)  the original theory was an outgrowth of an entirely unrelated area of philosophy.

Question 18

Mars moves in an elliptical orbit around the Sun. The Sun is located at

Accepted Answer

A)  the exact center of the ellipse. 
B)  the focus of the ellipse that is closer to the point where Mars moves fastest. 
C)  one end of the major axis of the ellipse. 
D)  the focus of the ellipse that is closer to the point where Mars moves slowest.

Question 19

The careful description of the velocity of a moving object at a particular time requires that one define the

Accepted Answer

A)  speed and acceleration of the object. 
B)  speed and direction of the moving object. 
C)  mass, speed, and position of the object. 
D)  speed (only) of the object.

Question 20

What was the conclusion of Tycho Brahe about the nature of the solar system?

Accepted Answer

A)  Tycho observed the phases of Venus and thus concluded that the solar system is heliocentric. 
B)  Tycho's observation of the Jovian system (Jupiter and its four large moons) convinced him that the solar system is heliocentric. 
C)  Tycho's failure to detect parallax motion for the stars convinced him that the solar system is geocentric. 
D)  Tycho's observations of the Sun convinced him that it is so large it must be the center of the solar system.

Exam 2: Gravitation and the Motion of the Planets