Lesson: Flow Rates of Faucets and RiversContributed by: Civil and Environmental Engineering Department, Colorado School of Mines
Educational Standards :
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Introduction/Motivation (Return to Contents)
The U.S. Geological Survey (USGS) has thousands of stream flow monitoring stations throughout all 50 states; the amount of data available is astounding. Teachers have endless creative possibilities when working with this data in their classroom, but unless students understand what stream flow is, and have a good concept of the magnitude of a given flow rate (often just a number on a computer screen), they will not get the maximum benefit from the unit. This Flow Rate Experiment helps ensure that students have good conceptual understandings of flow rate, as well as helps them become more familiar with the USGS website and online data searching.
The rate at which water flows is critical to many engineering situations. For example, civil engineers design stormwater drainage systems and canals based on a critical flow rate condition. For example, in an extreme storm event, water must flow in large quantities away from the storm area to prevent flooding, so civil engineers design drainage systems for extreme storm flow rates. As another example, fire fighters require a certain flow rate and water pressure to put out fires. So mechanical engineers design pump and delivery systems capable of providing the necessary flow rates and water pressures.
Lesson Background & Concepts for Teachers (Return to Contents)
Flow Rate: Flow rate is the volume of water passing a point in a fixed period of time. Flow rate is usually measured in cubic feet per second (cfs or ft³/sec) but could also be measured in gallons or liters per minute or second. For example, if a running faucet took one minute to fill a gallon container, its flow rate would be 1 gallon per minute. Water flow in a stream, river or pipe also has a flow rate. The flow rate in a river, stream or pipe can be determined by multiplying water velocity by the cross-sectional area. For example, if water was flowing through a 1 foot diameter pipe (area = 0.8 ft2) at 5 feet per second, the flow rate would be 0.8 ft2 x 5 ft/sec = 4 ft3/sec.
Teachers need to have a fair working knowledge of the USGS website, specifically USGS Current Water Data for the Nation (accessible at http://waterdata.usgs.gov/nwis/rt) before implementing this lesson in the classroom. The online User Guide goes into great detail about how to access the various kinds of available data. We recommended that you work through the User Guide and this activity before implementing in your class. Note that activity 2 of this lesson asks students to estimate the flow rate of a nearby river – one that they are presumably familiar with. Before implementing the Flow Rate lesson, determinei the flow rate in this river within the USGS website.
Associated Activities (Return to Contents)
Lesson Closure (Return to Contents)
At the end of this lesson, students should communicate differences between their hypothesis and the actual USGS data related to their understanding of flow rate.
Assessment (Return to Contents)
The goal of the Flow Rate Experiment is to help students gain a better understanding of flow rate, and to help them obtain a sense of scale for the flow rate in a river. The degree to which this is accomplished can be gauged by how well students are able to explain differences between their hypothesis and the USGS data.
Lesson Extension Activities (Return to Contents)
Have students determine flow rates of faucets, shower heads and garden hoses used in their homes or school.
In the Faucet Flow Rate activity, student teams analyzed their own data. Collect the data tables from all teams and have each student or team compare their results with those of other teams. Comparison analysis will vary if faucets were different. However, if faucets were similar, discrepancies in data results could be due to operator variance.
ContributorsBobby Rinehart, Karen Johnson, Mike Mooney
Copyright© 2013 by Regents of the University of Colorado; original © 2005 Colorado School of Mines
Supporting Program (Return to Contents)Civil and Environmental Engineering Department, Colorado School of Mines
Acknowledgements (Return to Contents)
This curriculum was created with support from the National Science Foundation. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.