This is a picture of the centripetal force model.

Centripetal Force Model

This is a simple model of centripetal force.

This elegant yet simple model gives a student with a visual impairment needed auditory input to understand the concept of centripetal force.

Centripetal force is the force that pulls a thing toward the center of rotation.  A commonly used example of centripetal force is the force applied to a rider as the roller coaster twirls around. 


Materials for this activity include a quart-size Ziploc baggy, a medium-size marble, and a funnel.
Materials for this activity include a quart-size Ziploc baggy, a medium-size marble, and a funnel.


  1. Place the funnel inside of the Ziploc bag.
  2. Place the marble inside of the funnel.
  3. Hold the Ziploc bag tight around the mouth of the funnel while rolling the marble around.


  1. The topic of centripetal force could be introduced by asking if students have observed the machine at amusement parks or museums in which kids put a coin and it rolls around and around eventually going through a hole in the bottom. Discuss this and other examples of centripetal force.
  2. While teaching this content, explain to students that this model represents centripetal force.
  3. While the Ziploc bag is held taut over the mouth of the funnel, have student swirl the funnel and allow the marble to roll around the funnel eventually going getting caught in the hole.
  4. If students struggle to swirl the funnel, describe the motion as similar to making little circles as done in P.E. class only motion is round and round on a vertical plane rather than horizontally.

NGSS Standards

3-PS2-1. Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.

This model was designed by Jim Clark, science teacher at TSBVI.

By Laura Hospitál

Collage of model of centripetal force

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