Hands-on Activity: Falling Water
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
For the entire class to share:
Introduction/Motivation (Return to Contents)
Who knows what energy is? (Answer: Something that can do work). Have you ever heard of potential or kinetic energy? Well, potential energy is simply the "stored" energy of an object. An object's potential energy depends partly on its height and gravity. Kinetic energy is the energy of the object in motion. As an object falls, or moves down an incline, its potential energy is converted into kinetic energy. So, a falling object (or one rolling or sliding down a hill) loses its potential energy as it increases its kinetic energy.
When we think of water, potential energy is the energy of the water as it sits calmly in a reservoir or lake. The kinetic energy of water is when it is rushing through a river, down a waterfall or through a hydroelectric power plant. The force of the kinetic energy is dependent on the height and mass of the falling water. Hydroelectric is when water is used to produce electricity. Civil engineers design and build dams and hydroelectric power plants that use the energy of falling water to turn the blades of turbines to generate electricity that we can use in our homes. So, it is actually the kinetic energy of water moving through a power plant that can produce electricity.
In this activity, we are going to drop water from different heights to demonstrate how the kinetic energy of water changes when it hits the floor. Engineers must understand how height affects the amount of kinetic energy so they create a reservoir that holds the proper amount of water and design a hydroelectric power plant that produces the right amount of electricity. Since water falls too fast for us to measure the velocity (or kinetic energy) of the water directly, we will measure the size of the splash produced to show us how much kinetic energy is there.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
With the Students
Safety Issues (Return to Contents)
Troubleshooting Tips (Return to Contents)
Make sure students fill their straw to the mark before each trial, otherwise the amounts will be inconsistent.
This activity works best if the teams drop the water onto a hard, flat surface.
Shorter students may require chairs or stools on which to stand when they drop the water.
Assessment (Return to Contents)
Voting: Ask a true/false question and have students vote by holding thumbs up for true and thumbs down for false. Tally the votes and write the totals on the board. Give the right answer.
Discussion Question: Ask a discussion question to get students to think about the upcoming activity. After soliciting answers, explain that these questions will be answered during the activity. Ask the students:
Activity Embedded Assessment
Prediction: Ask students to predict the outcome of the activity before the activity is performed. What will happen to the splash as it is dropped from increasing heights? Do you expect the size of the splash to increase or decrease with higher drop heights?
Design Decisions: As a class, design the parameters for your experiment, including determining standard methods to ensure experimental consistency in the following:
Worksheet: Have the student teams record measurements, answer questions, make calculations and graph data on the worksheet. Review their answers to gauge their mastery of the subject.
Concluding Discussion: Ask the students and discuss as a class:
Diagramming: Ask the students to illustrate the concept of energy transfer through drawing.
Engineering Application: Have students reflect on the following engineering applications for kinetic and potential energy. This assignment is suitable for a class discussion or a journal entry.
Activity Extensions (Return to Contents)
Test how changing the mass of the water drop affects the size of the splash produced. Try different sized drops for each height.
Math Problem Solving: Present the class with the following problems and ask the students to determine which case has the greater kinetic energy when it hits the ground. (Note: Greater height or mass = greater kinetic energy.)
Test how the angle at which water falls affects the size of the splash produced. See the Foundation for Water and Energy Education's Turning to Hydropower activity, "Will changing the slope of falling water affect how fast it flows?" at: http://www.fwee.org/TG/unit_2c.pdf.
Activity Scaling (Return to Contents)
References (Return to Contents)
The Artist with a Camera. Tennessee Valley Authority. Accessed October 31, 2005. (Story of TVA photographer Charles Krutch) http://www.tva.gov/heritage/camera/
The Nature of Water Power, Curriculum Units. Foundation for Water and Energy Education. Accessed October 27, 2005. (Activity adapted from this source.) http://www.fwee.org/TG/curriculum.html
Verdant Power, LLC. Accessed October 27, 2005. (Engineers who design underwater turbine power generating systems) http://www.verdantpower.com
ContributorsXochitl Zamora-Thompson, Sabre Duren, Natalie Mach, Malinda Schaefer Zarske, Denise Carlson
Copyright© 2005 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.