Periodic & Circular Motion: Centripetal Force

Develop an understanding of the relationship between centripetal force and its factors: circular speed, mass and radius.

Motion Sensors

Students discover that circular speed decreases as the mass is increased (holding radius and centripetal force constant). Enlarge graph.


Centrip. Force

As student swings the mass in a circle, the force is recorded by the force sensor, and this data can be used to determine the period. Students will use the period and radius to calculate circular speed. Enlarge image.


Speed vs Radius Graph

Students discover that the circular speed increases as the radius of the circle increases (holding mass and centripetal force constant). Enlarge graph.

Lab Summary:

In this 3-part activity, students will explore the relationship of centripetal force, circular speed, mass and radius.

In Part A, the radius and mass are held constant, and the circular
speed is changed.
In Part B, the radius and force are held constant, and mass is changed.
In Part C, the mass and force are constant, and the radius is changed.

Download free labs:

(student versions)

Xplorer GLX-based lab, Part A  (PDF, 912 KB)

Xplorer GLX-based lab, Part B  (PDF, 464 KB)

Xplorer GLX-based lab, Part C  (PDF, 1 MB)

Method:

Students will swing a mass on a string in a circular motion while the string is attached to a force sensor. Students will calculate the circular speed using the period and radius. The period is determined from the graph of force vs. time, as students can easily count the number of revolutions using this graph. In each of the 3 parts of this experiment, students will hold two of the remaining 3 factors (centripetal force, mass, and radius) constant. 

Here's What You Need:

Probeware

Other Materials

Lab Manual:

This activity is included in Physics with the Xplorer GLX (PS-2826), complete with Teacher Information pages, student instructions and handouts, and sample data for a total of 35 probeware-based labs. For your convenience, we offer bundles which provide the probeware necessary for the activities in the manual. For more information on these resources and bundles, click here.