Astronomy Practice questions Chapter 2

Galileo's early observations of the sky with his newly made telescope included A) the discovery of Pluto. B) the discovery of the phases of Venus. C) the discovery of of Jupiter's magnetosphere. D) the discovery of retrograde motion in planets.

B) the discovery of the phases of Venus.

The acceleration of an object is defined as A) the rate of changes of its speed. B) the rate of change of its velocity. C) the rate of change of its direction of travel. D) the rate of change of its position.

B) the rate of change of its velocity.

Kepler's third law tells us that A) the period of a planet in years is the same number as its semimajor axis in AU. B) the square of a planet's period in years is the same number as the cube of its semimajor axis in AU. C) the square of a planet's period in years is the same number as the fourth power of its semimajor axis in AU. D) the cube of a planet's period in years is the same number as the square of its semimajor axis in AU.

B) the square of a planet's period in years is the same number as the cube of its semimajor axis in AU.

Which fundamental particle is believed to create the physical property called "mass" when it interacts with other particles? A) The proton B) The neutrino C) The Higgs particle D) The WIMP (Weakly-Interacting Massive Particle)

C) The Higgs particle

Kepler's second law states that a planet moves fastest when it A) passes through the minor axis. B) is closest to the Sun. C) is farthest from the Sun. D) is at conjunction.

B) is closest to the Sun.

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

A) It was discovered by mathematical prediction using Newton's laws.

Two spaceships that have different masses but rocket engines of identical force are at rest in space. If they fire their rockets at the same time, which ship will speed up faster? A) The one with the lower mass B) The one with the higher mass C) They will increase speed at the same rate because they have identical rocket engines. D) They will not speed up at all, but move at a constant speed because they are in space and the rocket has nothing against which to push.

A) The one with the lower mass

What is the difference between the synodic and sidereal periods of a planet? A) The synodic period refers to the planet's period with respect to the Earth's motion, whereas the sidereal period is the true period with respect to the background stars. B) There is no difference; they are one and the same time period. The synodic period is the name used in the geocentric theory, whereas the sidereal period is the name used in the heliocentric theory. C) The synodic period refers to the planet's motion with respect to the background stars, whereas the sidereal period is the true period with respect to the Earth's motion. D) The synodic period refers to the planet's rotation around its axis, whereas the sidereal period is the time for one orbit.

A) The synodic period refers to the planet's period with respect to the Earth's motion, whereas the sidereal period is the true period with respect to the background stars.

When Mars is at opposition, it is A) high in the sky at midnight. B) high in the sky at sunset. C) high in the sky at noon. D) rising at about midnight.

A) high in the sky at midnight.

According to Newton's first law, A) if no net force is acting upon an object, then both the object's speed and direction of travel will be constant. B) the larger the rate of change of speed of an object, the larger the force acting upon the object. C) an applied force always causes a change in the speed of an object. D) an applied force always causes a change in the direction of travel of an object.

A) if no net force is acting upon an object, then both the object's speed and direction of travel will be constant.

The semimajor axis of an ellipse is A) the distance from the center of the ellipse to one end, along the largest diameter of the ellipse. B) the distance from the center to one side of the ellipse, along the shortest diameter of the ellipse. C) the distance from one focus to any point on the circumference of the ellipse. D) half the distance between the foci of the ellipse.

A) the distance from the center of the ellipse to one end, along the largest diameter of the ellipse.

Which of the following statements CORRECTLY states the significance of Galileo's observation that Jupiter has satellites (moons)? A) It showed that Jupiter must be four times the size of the Earth (because Jupiter has four moons and the Earth has one). B) It showed that bodies can orbit an object other than the Earth. C) It was interesting but had no other particular significance. D) It showed that Jupiter must orbit the Sun, not the Earth.

B) It showed that bodies can orbit an object other than the Earth.

Which of the following statements is a CORRECT version of Newton's third law? A) Whenever some object A exerts a force on some other object B, B must exert a force of equal magnitude on A in the same direction. B) Whenever some object A exerts a force on some other object B, B must exert a force of equal magnitude on A in the opposite direction. C) Whenever two forces act, they must be equal in magnitude and opposite in direction. D) Whenever any object feels some force, it must also feel another force of equal magnitude in the opposite direction from some other source.

B) Whenever some object A exerts a force on some other object B, B must exert a force of equal magnitude on A in the opposite direction.

An unbalanced force acting on an object will ALWAYS cause it to A) change its direction of travel. B) change its speed or its direction of travel or both. C) change its acceleration. D) change its speed.

B) change its speed or its direction of travel or both.

Kepler's first law states that a planet moves around the Sun A) in a circle, with the Sun at the center. B) in an elliptical orbit, with the Sun at one focus. C) in an elliptical orbit, with the Sun on the minor axis of the ellipse. D) in an elliptical orbit, with the Sun at the center of the ellipse.

B) in an elliptical orbit, with the Sun at one focus.

Kepler's second law states: A) A line joining a planet to the Sun moves equal distances along the planet's orbit in equal times. B) A line joining a planet to the Sun sweeps through equal angles in equal times. C) A line joining a planet to the Sun points in the same direction at all times. D) A line joining a planet to the Sun sweeps out equal areas in equal times.

D) A line joining a planet to the Sun sweeps out equal areas in equal times.

Which of the following four objects or persons is NOT accelerating? A) A bicyclist gradually slowing down on a straight road while coasting toward a stop sign B) A motorcyclist traveling around a circular racetrack at a constant speed C) An apple falling to the ground from an apple tree D) An Olympic swimmer exerting considerable force to maintain a constant speed in a straight line through the water

D) An Olympic swimmer exerting considerable force to maintain a constant speed in a straight line through the water

The Copernican system for planetary motions is A) Earth-centered, with the planets, the Sun, and the stars mounted on crystal spheres, pivoted to allow the correct motions around the Earth. B) Earth-centered, with the planets moving in epicycles around the Earth. C) Sun-centered, with the planets moving in elliptical orbits, the Sun being at one focus of the ellipse. D) Sun-centered, with the planets moving in perfect circles around the Sun.

D) Sun-centered, with the planets moving in perfect circles around the Sun.

Kepler's third law can be described in which of the following ways? A) The time to complete one revolution of its orbit is dependent upon the size or radius of the planet. B) The smaller the radius of a planet, the more rapidly it rotates on its axis. C) The smaller the orbit, the longer it takes for the planet to complete one revolution. D) The larger the orbit, the longer it takes for the planet to complete one revolution.

D) The larger the orbit, the longer it takes for the planet to complete one revolution.

When observing planetary motions from the Earth, the phrase "retrograde motion" refers to A) the apparent westward motion of the planet (and the Sun, the Moon, and stars) across the sky due to the rotation of the Earth. B) motion of the planet away from the Earth during part of its orbit. C) a slow eastward motion of the planet from night to night compared to the background stars. D) a slow westward motion of the planet from night to night compared to the background stars.

D) a slow westward motion of the planet from night to night compared to the background stars.

When a planet is seen at opposition, it is always A) at its most distant point from the Sun. B) at its closest point to the Sun. C) at its most distant point from the Earth. D) at its closest point to the Earth.

D) at its closest point to the Earth.

When Venus is at superior conjunction, A) it is at its smallest distance from the Earth. B) it is at its greatest angle from the Sun as seen from the Earth. C) its speed in its orbit has its greatest value. D) it is at its greatest distance from the Earth.

D) it is at its greatest distance from the Earth.

The phenomenon of parallax is A) the change in the apparent position of a nearby object compared to background objects as a result of the motion of the object. B) the change in direction of motion of a planet from retrograde to direct motion. C) the apparent change in angular size of an object as it moves toward or away from an observer. D) the change in apparent position of a nearby object compared to background objects as a result of the motion of the observer.

D) the change in apparent position of a nearby object compared to background objects as a result of the motion of the observer.

In the geocentric model of the solar system developed by Ptolemy, A) the planets move with varying speeds in elliptical orbits around the Earth. B) the planets move at constant speeds in circular orbits around the Earth. C) the planets move in circular epicycles around the Sun while the Sun moves in a circular orbit around the Earth. D) the planets move in circular epicycles while the centers of the epicycles move in circular orbits around the Earth.

D) the planets move in circular epicycles while the centers of the epicycles move in circular orbits around the Earth.

The force of gravity between two objects is proportional to A) the sum of their masses. B) the difference of their masses. C) the ratio of their masses. D) the product of their masses.

D) the product of their masses.

A person standing on a bathroom scale sees a reading on the scale of 148 pounds. This person is acted on by A) no forces at all. B) only one force (148 pounds, as shown by the reading on the scale). C) only one force of 296 pounds (the sum of 148 pounds from the Earth and 148 pounds by the scale). D) two forces of equal size acting in opposite directions.

D) two forces of equal size acting in opposite directions.