Which of the following best describes what we mean by the focal plane of a telescope? 

Newton’s second law of motion tells us that the net force applied to an object equals its 

Absolute zero is 

Professional astronomical telescopes generally have a much greater magnification than the telescopes you can buy in stores. 

Study this H-R diagram. Which of the following stars has (or had) the longest hydrogen burning lifetime? (The red arrows help you locate these stars on the diagram.)

Which of the following correctly states the luminosity-distance formula?

What is the main idea captured by this graph?

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

Study this H-R diagram. What is the spectral type of the star Sirius? (The red arrow helps you locate Sirius on the diagram.)

If you drop a rock from a great height, about how fast will it be falling after 5 seconds, neglecting air resistance?