The goal of this activity is for students to determine the relationship between the (angular or linear) velocity, radius, and mass on the centripetal force or acceleration necessary to keep an object moving in a circular path.

In the Preliminary Observations, students will observe an object that is swung on a string in a circular path. Students then explore force (or acceleration) and circular motion using a method of their choosing, though instructors may provide a limited number of choices.

During the subsequent inquiry process, students may use a variety of tools ranging from a mass on a string to the Centripetal Force Apparatus. This activity can also be done virtually using Pivot Interactives.

Students should finish the activity having evaluated data graphically and developed an expression relating a center-pointed (centripetal) net force to the properties of circular motion.


  • Design and perform an investigation.
  • Draw a conclusion from evidence.
  • Understand that the centripetal force acting on (or the centripetal acceleration of) an object moving in a circular pattern is governed by one of two relationships