Astronomy: Orbits and Motion(ch 3)

The 17th century astronomer who kept a roughly 20 year continuous record of the positions of the Sun, Moon, and planets was:

• a. Tycho Brahe

• b. Galileo Galilei

• c. Isaac Newton

• d. Nicolaus Copernicus

The scientist who formulated the three laws of planetary motion by analyzing the data on the precise location of planets in the sky was:

• a. Tycho Brahe

• b. Galileo Galilei

• c. Johannes Kepler

• d. J. C. Adams

In an ellipse, the ratio of the distance between the foci and the length of the major axis is called:

• a. the eccentricity

• b. the semi-major axis

• c. perihelion

• d. the astronomical unit

When a planet, in its orbit, is closer to the Sun, it:

• a. moves slower than average

• b. reflects less sunlight than average

• c. feels less gravitational pull than average

• d. moves faster than average

According to Kepler's third law, there is a relationship between the time a planet takes to revolve around the Sun and its

• a. size

• b. period of rotation

• c. distance from the Sun

• d. eccentricity

When NASA and a group of astronomers sent up a spacecraft designed to find planets orbiting other stars, they named it after Kepler.  Why was this an appropriate name?

• a. Kepler used his telescope to find the first planet orbiting another star

• b. Kepler was the first person to express the law of universal gravity in mathematical terms

• c. Kepler figured out the rules of planetary motion, which planets in our solar system and 

  planets elsewhere must obey

• d. Kepler was the first person to suggest how to launch rockets into space

Newton showed that to change the direction in which an object is moving, one needs to apply:

• a. a force

• b. an orbit

• c. an inertia

• perigee

Which of the following statements about forces is FALSE?

• a. forces change the momentum of a body

• b. forces cause an acceleration to take place

• c. forces always occur in equal and opposite pairs

• d. there are places on Earth where all forces are absent

A single star in the process of forming starts by spinning slowly (while it is quite large and relatively cool.)  As the star collapses under the pull of its own gravity, its size decreases.  As a result, its rate of spinning:

• a. will increase

• b. will decrease

• c. will stay the same

• d. will either increase or decrease depending on the star's temperature

After a long night of cramming for a test, your college room-mate hits his head forcefully against the wall of your room in despair.  According to Newton’s 3rd Law, as he exerts a force against the wall, there must be an equal and opposite force.  How does that opposite force show itself in this case?

• a. Your room-mate is pulled downward by gravity

• b. The wall exerts a force on your room-mate’s head and he has a headache

• c. The wall has a huge dent in it

• d. There is an exception to the Law for solid objects like walls, so there is no opposite force