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Sideways Icicles

Icicles on a roof growing sideways because of prevailing wind currents demonstrates that the applied wind force partially overcomes the gravitational force downward.
 

Location
Farley, Iowa, Dubuque County

Possible Guiding, Compelling and/or Anchoring Questions

  • What forces are involved?
  • How long were the forces affecting the icicles? 
  • Why did the phenomenon occur here but not elsewhere?

Classroom Suggestions

  • Topics: Forces in Two Dimensions, Addition of Vectors
  • Show the photo of the icicles and have students generate questions about them. 
  • Enlarge the phenomenon photo and zoom in on the icicles for a closer look or to measure angles.
  • To focus on forces, use the Sideways Icicles Video clip showing the wind pattern on the building. 
  • Additional photos: Ice formations on trees in wind  photographed by Marko Korosec: Extreme conditions of humidity, freezing temperatures, and high wind created ice formations that are nearly horizontal. 

Related Resources

  • How Are Icicles Formed: This article explains the process of icicle formation and ties it to stalactites in caves.
  • Kinematics in Two Dimensions: An Introduction: This lesson explains how motion can be described as made up of vertical and horizontal components. It also features links to other resources, and is suitable for teacher background or a physics class.
  • The Physics Classroom: Addition of Forces: This article explains the process of adding vectors to find the net force. It also features links to other resources, and is suitable for teacher background or a physics class.
  • The Physics Classroom : Vector Addition Interactive: This lesson contains teaching notes and a link to an interactive to help teach addition of vectors. Students can insert the vectors involved and it will give the resultant magnitude and angle.

Iowa Core Alignment

Grade
High School (9-12)
Disciplinary Core Idea
PS2: Motion and Stability: Forces and Interactions

Credit Info

Submitted by Diane May

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