Question 1

Which of these four objects or persons is NOT accelerating?

Accepted Answer

A)  bicyclist gradually slowing down on a straight road while coasting toward a stop sign 
B)  motorcyclist traveling around a circular racetrack at a constant speed 
C)  apple falling to the ground from an apple tree 
D)  Olympic swimmer exerting considerable force to maintain a constant speed in a straight line through the water

Question 2

The ancient Greek thinker whose model of the universe came to dominate the medieval world was

Accepted Answer

A)  Archimedes. 
B)  Alexander. 
C)  Ptolemy. 
D)  Zorba.

Question 3

The planet Jupiter travels in an elliptical orbit. The Sun is at one focus of this ellipse. What is at the other focus?

Accepted Answer

A)  Earth 
B)  Ganymede, the largest of Jupiter's moons 
C)  Trojan asteroids 
D)  nothing

Question 4

Which object was discovered mathematically using Newton's laws before it was discovered observationally through the telescope?

Accepted Answer

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

Question 5

If light takes about 8.3 minutes to travel from the Sun to Earth, approximately how much longer would light take to travel from Jupiter to Earth when Jupiter is at conjunction (appearing closest to the Sun in the sky) than when it is at opposition (on the opposite side of Earth from the Sun)? (Assume that light from Jupiter is not blocked by the Sun at conjunction. A diagram might help.)

Accepted Answer

A)  8.3 minutes 
B)  16.6 minutes 
C)  43.2 minutes 
D)  There is insufficient information to answer the question.

Question 6

The strength of gravity on Mars is about 40% of that on Earth. If an astronaut were to visit Mars, what would happen to their mass and weight compared to when they were on Earth?

Accepted Answer

A)  Their weight would be the same, but their mass would be less. 
B)  Their weight and mass would both be less than when they were on Earth. 
C)  Their weight and mass would both be unchanged from when they were on Earth. 
D)  Their mass would be the same, but their weight would be less.

Question 7

The observation by Tycho Brahe of a supernova in 1572 was significant because it

Accepted Answer

A)  showed a parallax (relative apparent motion) that proved it to be more distant than the Moon. 
B)  showed motion in a circular orbit. 
C)  proved Kepler's three laws. 
D)  proved the heliocentric theory.

Question 8

A space probe is put into a circular orbit around the Sun at a distance of exactly 2 au from the Sun. According to Kepler's third law, how long does it take this probe to orbit the Sun once?

Accepted Answer

A)  1.6 years (cube root of 4) 
B)  1 year 
C)  8 years 
D)  2.8 years (square root of 8)

Question 9

In the simplified version of Kepler's third law, P2 = a3, the units of the orbital period P and the semimajor axis of the ellipse a must be, respectively,

Accepted Answer

A)  years and light-years. 
B)  years and astronomical units. 
C)  years and meters. 
D)  seconds and meters.

Question 10

Greatest elongation in a planetary orbit occurs when the angle from the

Accepted Answer

A)  Earth to the planet and then to the Sun has its greatest possible value. 
B)  the Sun to Earth and then to the planet is 90°. 
C)  Earth to the Sun and then to the planet is 90°. 
D)  Sun to the planet and then to Earth is 90°.

Question 11

What is the minimum number of forces that need to be applied to a body in space to keep it moving with a constant velocity?

Accepted Answer

A)  none 
B)  one force, in a direction opposite to the direction of motion 
C)  two unequal forces 
D)  one force, in the direction of motion

Question 12

Tycho Brahe demonstrated that the supernova of 1572 was NOT a nearby event (close to Earth) by

Accepted Answer

A)  proving that it did not show parallax over the course of one night. 
B)  showing that it did not pass in front of the Sun at conjunction. 
C)  proving that it did not move past the background stars like a planet in our solar system. 
D)  showing that it did not get brighter and fainter as Earth moved toward and away from it over the course of a year.

Question 13

When Saturn is closest to Earth, it is at

Accepted Answer

A)  greatest elongation (about 47° from the Sun). 
B)  opposition. 
C)  conjunction. 
D)  inferior conjunction.

Question 14

One of the major contributions of Galileo Galilei to the development of modern astronomy was

Accepted Answer

A)  use of parallax to prove that Earth moves around the Sun. 
B)  proof that planetary orbits are ellipses. 
C)  development of the first mathematical heliocentric model of the solar system. 
D)  discovery of the satellites (moons) of Jupiter.

Question 15

A certain nearby star in the Milky Way is measured to be about 750 pc from Earth. Expressed in light-years, the distance is approximately

Accepted Answer

A)  1500 ly. 
B)  4.7 × 107 ly. 
C)  230 ly. 
D)  2445 ly.

Question 16

In 2014 A.D., an inhabitant of a planet orbiting a distant star observes the flash of the first nuclear explosion on Earth, which occurred in July 1945. Approximately how far away is his solar system from Earth?

Accepted Answer

A)  219 pc 
B)  21.2 pc 
C)  about 0.07 pc 
D)  2.06 pc

Question 17

If a person travels from Earth to the Moon, which of these quantities will be unchanged?

Accepted Answer

A)  the gravitational force acting on the person 
B)  the person's mass 
C)  the person's weight in pounds 
D)  the person's weight in newtons

Question 18

To which point in a planetary orbit does the word "perihelion" refer?

Accepted Answer

A)  point farthest from the Sun 
B)  precise center of the orbit 
C)  "other" focus (the one not occupied by the Sun) 
D)  point closest to the Sun

Question 19

An astronomical unit (au) is a unit of

Accepted Answer

A)  time equal to the time taken for light to travel from the Sun to Earth. 
B)  length, defined as the wavelength of light from krypton gas. 
C)  length, the average distance between the Sun and Earth. 
D)  mass equal to 1 solar mass.

Question 20

A major theme of ancient Greek philosophy was that stars and planets in the sky

Accepted Answer

A)  followed patterns that could be described logically. 
B)  could be controlled by the thoughts and actions of humans. 
C)  were at the mercy of gods and spirits, and the behavior of these objects depended on their whims. 
D)  behaved chaotically, and their future behavior was totally unpredictable.

Exam 2: Gravitation and the Motion of the Planets