8. Centripetal Forces & Gravitation

In a binary star system, astronomers are able to detect the dimmer star because its gravity causes the bright star to what?

Which explanation best describes why Earth observers always see the same face of the $Moon$?

Which of the following best describes a correctly drawn gravitational force field diagram around a point mass located at the origin in two dimensions?

If the Earth shrank in size but its mass remained unchanged, what would happen to the gravitational acceleration $g$ at its surface?

At which location on $\mathrm{Earth}$ is the centripetal force required to keep an object moving with the $\mathrm{Moon}$ (due to the $\mathrm{Moon}$'s gravity) the greatest?

A small mass $m$ moves in a circular orbit of radius $r$ under the influence of a uniform gravitational field with acceleration $g$. What is the orbital period $t$? Express your answer in terms of $g$, $m$, $r$, and $\pi$.

Why does an object weigh more at sea level by the ocean than it does at the top of a mountain, assuming the object's mass remains constant?

High tides are created on Earth when nearby celestial bodies create what change in the oceans?

Why do stars appear to change position during the night when observed from Earth?

Which of the following best describes one way that spring tides differ from regular ($\mathrm{neap}$) tides?

Which of the following pieces of information do astronomers use to calculate the age of the universe?

Inside the Sun, which two forces are in balance to maintain its stable structure?

Which of the following actions would best help an astronaut avoid floating away in space due to gravitational forces in $2D$?

Why is the Milky Way galaxy not expanding together with the rest of the universe?

In the context of gravitational forces in two dimensions, what is the downward pull on an object due to gravity commonly called?