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Global Scales
An Investigation of Barometric Pressure and Gravitational Pull: Does It Influence Body Weight?
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Author Contact Information
Sandra Kolb, on leave from Central Kitsap School District, Silverdale, Washington (2000/2001 TEArctic)
Rick Griffith, Fairview Jr. High, Central Kitsap School District, Silverdale, Washington
Overview
In this activity students will use the Internet to investigate and compare/contrast body weights at the S. Pole to different regions around the world (N. Pole, Equator, Seattle, etc.).
Students will:
define barometric pressure and gravitational pull
describe how barometric pressure and gravitational pull affect body weight
apply knowledge of the effects of barometric pressure and gravitational pull on body weight to determine its effects at the South Pole and other regions of the world
Grade Level/Discipline
Grades 7/8, cross-curriculum Math and Physical Science
National Standards
Unifying concepts and processes in science
Physical science
Science as inquiry
Pre-activity set-up
Pre-teach barometric pressure and gravitational pull Experiment: This activity may be used to pre-teach barometric pressure. Cut off the neck of a balloon and place it over the mouth of a coffee can. The balloon needs to be even with the top of the can. Place a rubber band over the balloon onto the can so the balloon will stay on the can. Tape a straw onto the balloon. The pressure of the day can be observed. If it is high pressure the balloon will be pressed in and the straw will be pointed up, if the pressure is low the balloon will be raised and the straw will be pointed down. A graph can be made and placed next to the straw to actually measure how much the pressure has gone up or down.
Locate and bookmark Sandi Kolb's journal entry of 5 January 1997 (../../expedition/2_kolbletters_Jan_5.html)
Locate and bookmark the GLACIER website for weather reports
Locate and bookmark the South Pole Station website
Locate and bookmark local weather station and airport websites of choice
Prepare examples of graphs
Materials
Computers with internet access
Bathroom scale
Recording paper for weather data
Collected data on barometric pressure and gravitational pull
Colored pencils or markers
Graph paper
Poster paper
Time Frame
15 minutes each class period graphing barometric pressure from students' hometown, etc. and the South Pole Station over a selected period of time
Three to five 50-minute class periods
Engagement and Exploration (Student Inquiry Activity
Introduce with the following questions and discussion points while emphasizing concepts:
What do we mean when we say we are weightless?
Does weight vary at different locations?
Are we ever weightless on earth?
Where do we need to go to be weightless?
Point out that we are never truly weightless. We always have a tiny bit of weight because there is a tiny bit of gravity between the earth and the moon. Anytime there are 2 parcticles of matter there’s always weight because there is always gravity. Gravity is based upon the distance between two objects and the mass of the two objects.
What affects body weight? Point out that body weight can be either increased or decreased by these factors. Guide the students to understand that the following factors affect body weight:
force of gravity
centrifugal force
altitude
gravity
barometric pressure
Probing Question Do you think body weight could be different at the S. Pole compared to other regions around the world (N. Pole, Equator, Seattle, etc.)?
Brainstorm (no suggestions are wrong) while writing student ideas on a transparency or other visual aid. Discuss ideas AFTER brainstorming and why they may be correct or incorrect. Emphasize concepts.
Explanation (Discussing)
What is barometric pressure?
Why and how does barometric pressure change?
What determines body weight? (This is a review from the above material to link it to this discussion.)
force of gravity
centrifugal force
altitude
gravity
barometric pressure
How and why does barometric pressure affect body weight?
How and why does gravitational pull affect body weight?
Point out that the level of change of weight will occur at the 100ths place. This exercise requires scientific accuracy and precision of measurement.
Ask students to brainstorm examples for this question: Under what circumstances might we need to measure at this precision? Point out the roles that money or safety play in precision of measurement. Some examples the students may suggest are:
gems
precious metals
pharmaceuticals
Elaboration (Polar Applications)
Why do barometric pressure and gravitational pull at different regions of the world affect body weight?
Why and how are barometric pressure and gravitational pull different at various regions of the world?
Exchange (Students Draw Conclusions)
Students may choose to work either alone or in pairs to investigate (formulas provided) own body weight as compared and contrasted to different regions around the world (S. Pole, N. Pole, Equator, Seattle, etc.). Using graphs, students will prepare a presentation for the class.
Extensions:
Determine body weight on the moon. Compare and contrast to body weight on earth. Explain. Develop a visual aid for display and present findings to the class.
Calculate body weights on all planets. Compare and contrast to each other and planet earth. Explain.
Develop a visual aid for display and present findings to the class. Resource: Click on "Explore the Planets" at http://www.swcp.com/~tasa/
Resources
Internet for live daily reports:
HANDBOOK FOR CHEMISTRY AND PHYSICS 79th edition, David R. Lide editor-in-chief, 1998-1999, CRC Press, N.Y.
Click on "Explore the Planets" at http://www.swcp.com/~tasa/
Evaluation (Assessing Student Performance)
Students will present their findings to the class using graphs while showing/explaining their mathematical calculations. They will explain why weight is different at the various locations in terms of gravitational pull and barometric pressure.
The teacher will evaluate the presentations using a rubric and check mathematics and graphing for accuracy.
Students' graphs/charts will be displayed in the classroom.
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