CHAPTER 15

Gravitation and Circular Motion

IN THIS CHAPTER
Summary: When an object moves in a circle, it is accelerating toward the center of the circle. Any two massive objects attract each other
due to gravity.

Key Ideas

        Centripetal (center-seeking)    acceleration    is  equal   to      .

        Circular    motion  (and    gravitation)    problems    still   require a   free-body   diagram and the four-step

problem-solving process.

        The gravitational   force   between two objects is  bigger  for bigger  masses, and smaller for larger

separations between the objects.

        Kepler’s    laws    apply   to  the orbits  of  planets.

Relevant Equations

Centripetal acceleration:

Gravitational force between any two masses:

Gravitational potential energy a long way from a planet:

It might seem odd that we’re covering gravitation and circular motion in the same chapter. After all, one
of these topics relates to the attractive force exerted between two massive objects, and the other one