Exam 3: Orbits and Gravity

Why do many people consider Isaac Newton one of the greatest scientists who ever lived?

We now know that the orbit of a stable planet around a star like the Sun is always in the shape of:

Why do astronauts (and cans of soft drink) float around in the Shuttle instead of falling?

Astronomers discover a new comet that orbits the Sun, but has its aphelion (the furthest point in its orbit) beyond Neptune. Astronomers studying this comet have the right to expect that it:

An astronomy textbook, when printed out, weighs four pounds on the surface of the Earth. After finishing your course, you are so tired of the book, you arrange for NASA to shoot it into space. When it is twice as far from the center of the Earth than when you were reading it, what would it weigh? (Note, assume that the book has been moving away from the Earth, not falling freely around it.)

Which of the following has the greatest density?

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

Which of the following statements about forces is FALSE?

The planet in our solar system with the shortest period of revolution is:

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

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

The idea that objects (in the absence of an outside force) tend to continue doing what they are already doing is called the law of

When a comet like Comet Hale-Bopp comes closest to the Sun in its orbit, we say that it is at:

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

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?