8. Centripetal Forces & Gravitation

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?

Why do we always see the same side of the $Moon$ from $Earth$?

The luminosity of a quasar is generated in a region approximately the size of which of the following?

How does your $mass$ on the $Moon$ compare to your $mass$ on $Earth$?

According to Newton's law of universal gravitation, what happens to the magnitude of the gravitational force between two objects as the distance between them increases?

Why does Mercury have so little gas in its atmosphere compared to other planets?

The yearly cycle of seasons on $\mathrm{Earth}$ is caused by what motion of $\mathrm{Earth}$?

If the Earth rotated more slowly than it currently does, which of the following would most likely occur?

In the context of gravitational forces in two dimensions, what happens if you try to move two atoms very close to each other?

Why do most coastal locations experience two high tides each day, approximately $12$ hours apart?

The measure of gravity on Earth determines our $\mathrm{\_\_\_\_\_\_\_\_\_\_}$.