Exam 2: Gravitation and the Motion of the Planets

In Ptolemy's geocentric theory of the solar system, what name is given to the small circle around which the planet moves while the center of this circle orbits Earth?

In the Greek planetary model, the deferent is the

An inferior planet will be closest to Earth when it is at

At what position in its orbit does an inferior planet appear to be moving (for a day or two) more or less directly toward Earth? See Figure 2-4.

The retrograde portion of a planet's motion has what duration?

Nicolaus Copernicus was the first person to

The purpose of describing planetary orbits in terms of epicycles and deferents was to account for the

In the geocentric universe, when is the planet closest to Earth?

What is the angular momentum, L, of an object?

A rocket that is accelerated by the force from the ejection of large quantities of hot gases represents an example of which physical law originally stated by Newton?

Which of these planetary configurations is NOT possible for the planet Mercury?

Each planet moves along an elliptical path with the Sun at one focus of the ellipse. What is at the other focus?

If an astronaut landed on a planet of the same radius as Earth but 4 times the mass, then the astronaut's weight on the planet would be

In following the principles of the scientific method, a theory proposed to explain a given phenomenon must

When Mars is at opposition, it is

Tycho Brahe formulated a model of the solar system that was characterized by

Who predicted the existence of the planet Neptune before it was discovered observationally?

How many forces need to be applied to a body in space to keep it moving with a constant velocity?

The synodic period of a planet is defined as the time between two successive

Which of these statements is a correct version of Newton's third law?