Objectives 1
Department of Earth Science |Northeastern Illinois University
Daily Objectives #2 (January 15, 2009)                                        Dr. Sanders

By the end of today's class, you should be able to do the following:

v From last time: Describe the purpose and function of a rain barrel, and make quantitative calculations to estimate how a rain barrel is involved in the water budget of a residential property in Chicago.

v
New this time: Use concepts of length, area, volume, and flow rate to quantify hydrologic variables.

v  Solve a hydrologic problem in a sequence of logical steps, using reasonable units, significant figures, and dimensional analysis.

Our agenda today:

Teams get together to go over their calculations

How big is the property?  How does the area compare to an acre?
Describe how big an acre is in non-technical terms.

How much of the property is in garden plots?
What is the area of the roof?

If there are differences between answers, what accounts for them?

What is a typical rainfall in Chicago?  (cite your sources)

What depth annual precipitation do we get in Chicago?
What volume annual precipitation do we get in Chicago?

Problem-solving:
See "
Hints for Solving Quantitative Problems".

Dimensional analysis: using units of measurement to help solve problems.

Significant figures: what is the appropriate number to report?

Now let's move on to the rest of the questions.  Answer them using dimensional analysis and paying attention to significant figures:

How much rain will the roof collect in a typical rainfall?

Are two barrels enough to store water from a typical rainfall?
Are two barrels enough for me to store water to irrigate my entire garden?

--------------------------------------------------------
Groups that finish early should consider these questions:
• If the rain falls at a rate of 1 inch per hour, how long would it take to fill a rain barrel?
• How heavy would a full rain barrel be?

How big are the differences between answers?  How much difference indicates "the same amount", and how much difference indicates a "real" difference?

Homework:  For Tuesday, as a group (one set of answers for the whole group), complete Homework #1.

Department of Earth Science | Northeastern Illinois University

© 2009 Laura L. Sanders.  Last updated January 15, 2009.