What is the gravitational force of the sun on a book on the earth's surface if the sun's mass is and the earth-sun distance is ?

The mass and radius of a planet’s moon are and respectively.

With what minimum speed would a bullet have to be fired horizontally near the surface of this moon in order for it to never hit the ground?

(Note: You can treat the moon as a smooth sphere, and assume there’s no atmosphere.)

Two spheres of equal mass are isolated in space, and are separated by a distance . If that distance is doubled, by what factor does the gravitational force between the two spheres change?

Two spheres of equal mass are isolated in space. If the mass of one sphere is doubled, by what factor does the gravitational force experienced by the two spheres change?

You are riding in an elevator that is accelerating upwards at , when you note that a block suspended vertically from a spring scale gives a reading of .

What does the spring scale read when the elevator is descending at constant speed?

With what minimum velocity must a rocket be launched from the surface of the moon in order to not fall back down due to the moon's gravity?

The mass of the moon is and its radius is .