Physics Lesson: Force and Pressure
Field Museum Lesson Extensions
A. Related Exhibitions:
1. Native North Americans Hall, "Indians of the Woodlands: Great Lakes" section (just beyond the Webber Gallery). You will find 8 pairs of snowshoes used by Native peoples in the middle and eastern part of Canada and Midwestern U.S.
2. The Alsdorf Hall of Northwest Coast and Arctic Peoples, Northwest Coast "Village and Society" and "Fishing, Hunting and Gathering sections. You will find 3 pairs of snowshoes.
This extension of the Force and Pressure Lesson directs you to travel through the above exhibitions to find, measure, and sketch snowshoes made by Native peoples. At each stop where you find a snowshoe, you will measure the dimensions of the shoe, sketch a scale model, and then calculate an approximate surface area. You will then determine the pressure applied by a hypothetical 670 Newton (N) human who would use the shoe. You will consider how a snowshoe’s control of pressure on deep snow prevents a human from sinking.
What you will need to bring with you: a tape measure, calculator, pencil/pen, and a clipboard.
For each of the eleven pairs of snowshoes, perform the following procedures:
1) In the provided data tables (see following pages), make a scale drawing of the snowshoe on the grid.
a) Use a tape measure to measure the length of the snowshoe as well as its width. The snowshoes will be in exhibit cases and you will have to do your best to measure the shoes from a distance. Carefully line up the tape at one end and then move your head from one end of the shoe to the other to take a length reading. Do the same for the width at the widest part of the shoe. If the shoe is positioned too high in the exhibit case, then make a best estimate of these measurements.
b) Decide on a scale for the grid on your data sheet. For example, depending on the size of the shoe, you might want to use 20 cm, 25 cm, 40 cm, or any convenient interval so that the length and the width of the shoe can fit into the grid.
c) Convert your interval unit from centimeters to meters by moving the decimal point 2 places to the left. For example, 25 cm = 0.25 m.
d) Draw your shoe to scale. Record your grid scale in the data section.
2) Record a description of your shoe using the following descriptors:
a) “Bear paw”: Use this term if the frame is oval in shape and does not have a long tail on one or both ends. This type of shoe was used for maneuverability in heavily forested areas or areas of thick underbrush. It was not appropriate for deep powder and was not used for lengthy, fast travel.
b) “Beaver tail”: Use this term for a shoe with a teardrop shape and with a long narrow tail on one end. The shoe might or might not have an upturned toe. This shoe was used in the wide-open spaces of prairie, field, and savannah and traveled well on established snow trails. It was not appropriate for blazing trails in deep powder. An upturned toe of the shoe protected against tripping by preventing a fast-moving person from catching the front end of the shoe in the snow.
c) “Athabaskan”: Use this term for a shoe with an extremely long and narrow design. The shoe was used for fast travel in open areas with deep snow. It had a narrow tail at one or both ends, with or without an upturned toe. The shoe was similar to the beaver tail, but not teardrop shaped. It was not appropriate for moving in areas where frequent turns were required (For example, in a forested area).
3) Record the name of the Native peoples that used the shoe (For example: Eastern Chippewa of Canada).
4) Look at the exhibit case for any description or evidence of when the snowshoe was most often used. There may be a written description near the shoe, or you might see hunting gear nearby, or the snowshoe might be a part of the everyday items used by the people. Record this in the results table.
5) Determine the area of your shoe by counting the squares that fill the drawing.
a) You’ll have to estimate the sum of the partial squares that reside within the borders of your drawing. If a third of a square is within the borders, add 0.33 to your total. If a fourth of a square is with the borders, add 0.25, etc.
b) Calculate the area of one grid square by squaring the length you chose for your scale in 1c. For example, if you chose 0.20 m as the length of one grid, the area would be
(0.20 m)2, or 0.040 m2.
c) Find the surface area of the shoe. To do this, multiply the sum of squares within the borders of your drawing by the area of a grid square. For example, if you had a total of 11 squares within your drawing and a grid area of 0.040 m2, the shoe area would be
11 x 0.040 m2 = 44 m2.
d) Record the area of the shoe in the results table.
6) Determine the pressure that a 670 N (150 lb.) human would exert on the snow using the shoe. The units will be in Pascals (Pa) when you divide the force in Newtons (N) by the area in square meters (m2). Put the calculated pressures in the results table. Think about how the pressure on the snow from a snowshoe is different from the pressure on the snow from a human foot. In the results pages, write how a snowshoe adjusts pressure and prevents a person from sinking into the snow.
7) Diverse Native peoples in North America lived over large stretches of land. For this investigation, one estimated location for the specific Native group that used the snowshoe has been provided on the attached map. Find the letter designation for this location and then read the information about each location given on the attached information sheet. Record the approximate average annual snowfall and ecosystem information on the results sheet.
8) Determine if there is a correlation between the type of snowshoe you have observed and amount of snowfall, ecosystem, or possible use of the shoe. You might find a correlation between the surface area of the shoe and the amount of snow on the ground. Can you explain this? Or, you might find a correlation between the shape of the snowshoe and the description of the ecosystem. Can you explain this? Or, you might find a correlation between the shape and the use. Can you explain this?
B. Harris Educational Loan Center Resources:
1. Native Peoples of Illinois: Woodland and Mississippi slides. Prepare for your expedition by learning about some of the early Native peoples here in the Midwest.
2. Northwest Coast Peoples slides. Long winters and deep snow make every day a challenge for some Native peoples of the Northwest Coast. Discover how Native peoples have overcome the obstacles of living in a formidable environment.
3. Woodland Peoples and Their Environment slides. More information about the Native peoples whose art, tools, weapons, and lifestyles are on display in some of the Museum’s exhibitions.
4. Mammal, Snowshoe Hare Exhibit Case. Early peoples may have gotten the idea to build a snowshoe by observing animals that live in cold climates. This exhibit case shows one of these animals. Compare the foot size of this animal to others of similar weight. Can you estimate by how much the force on the snow has been reduced because of the large surface area of the hind foot?
C. Field Museum Website Resources:
1. Living Together: Common Concerns, Different Responses: Snowshoes and Reef Shoes: www.fieldmuseum.org/exhibits/exhibit_sites/living_together/shoes2.htm
A picture of snowshoes made by the Maidu peoples, early 20th century, California.
Information from the Web page:
“Environment is the factor that influenced how these pairs of shoes were made and used.
Protecting the feet in different terrains is the common concern that these pairs of shoes address.
These pairs of shoes show different responses to protecting the feet. Snowshoes protect the feet from snow filled terrain, while wet weather shoes keep the feet above rainy ground.”
Questions: How do the snowshoes protect the wearer? Can you identify the environment in which these snowshoes would have been used? Open field? Forest? Deep snow? Shallow and packed snow on a trail?
2. Additional Website Resource: Smithsonian American Art Museum:
americanart.si.edu/collections/search/artwork/?id=4382
Question: Can you identify the different types of snowshoes in this painting by George Catlin entitled, Snowshoe Dance at the First Snowfall? Can you match each snowshoe with how and where it might have been used?
Physics Lesson: Force and Pressure
Field Museum Extensions: Data Collection Page
Snowshoe sketches from Native North Americans Hall: Indians of the Woodlands: Great Lakes
Snowshoe Sketch / Scale: Grid Length in Meters / Description of Snowshoe / Native Group that Created/Used the Snowshoe1 /
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Physics Lesson: Force and Pressure
Field Museum Extensions; Data Collection Page
Snowshoe sketches from The Aldorf Hall of Northwest Coast and Arctic Peoples: Northwest Coast Village and Society section and the Fishing, Hunting and Gathering section
Snowshoe Sketch / Scale: Grid Length in Meters / Description of Snowshoe / Native Group that Created/Used the Snowshoe1 /
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Physics Lesson: Force and Pressure
Field Museum Lesson Extensions: Results Page
Snowshoes from the Native North Americans Hall: Indians of the Woodlands: Great Lakes
Snowshoe Area (m2) / Pressure Applied by a Human with a Weight of F=670 NP = F/A
P in Pascals,
F in N, A in m2 / Average Annual Snowfall (cm) / Ecosystem Description / Possible Use for the Snowshoe (Long-distance travel, hunting, daily work, etc.)
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Lesson: Force and Pressure
Field Museum Lesson Extensions: Results Page
Snowshoes from The Aldorf Hall of Northwest Coast and Arctic Peoples: Northwest Coast Village and Society section and the Fishing, Hunting and Gathering section
Snowshoe Area (m2) / Pressure Applied by a Human with a Weight of F=670 NP = F/A
P in Pascals, F in N, A in m2 / Average Annual Snowfall (cm) / Ecosystem Description / Possible Use for the Snowshoe (Long-distance travel, hunting, daily work, etc.)
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Question: How does a snowshoe prevent a person from sinking into the snow?
Question: Is there a correlation between the shape and/or size of the snowshoes, and the:
a) Average snowfall?
b) Ecosystem?
c) Use?
Explain:
Physics Lesson: Force and Pressure
Field Museum Lesson Extensions: Background Information*
The attached map shows the approximate locations where the Native peoples highlighted in the noted exhibitions lived. The key is as follows:
A. Early Montagnais-Naskapi peoples lived in an area that receives an annual snowfall of close to 200 cm. The area is open boreal woodland—a forested area with both coniferous and broadleaf trees.
B. Early Northern Chippewa peoples lived in an area that receives an annual snowfall of about 25 to 50 cm. The area was a mix of forest and plain with open areas and savannahs. The shallow snow in the open fields was mostly light powder (not wet and packed).
C. Early Eastern Chippewa peoples (Canada) lived in an area that received 100-200 cm of snow annually. The area was mostly forested.
D. Early Naskapi peoples (Labrador, Canada) lived in an area that received up to 100 cm of snow annually. The snow could be wet and heavy. The area was rocky, hilly, and forested.
E. Early Chippewa peoples of the Great Lakes lived in an area that received an annual snowfall of about 100 cm. The area was densely forested.
F. Early Potawatomi peoples (S. Wisconsin) lived in an area that received an annual snowfall of about 75 cm. The area was forested.
G. Various early Northwest Coast peoples lived in areas that received heavy annual snowfalls of 200 cm and more. The hilly ecosystems were forested.
H. Early Inuit peoples near Kotzebue Sound, Alaska lived in an area that receives about 50 cm of annual snowfall. The area is mostly flat tundra.
*Teacher Note: The descendants of the early Native peoples in the Americas live throughout North, Central, South America and the Caribbean—and around the globe. Many early cultures were destroyed. Others endured to carry their languages, histories, and cultural traditions forward into the future. Today, Native peoples draw on and honor the traditions of their ancestors. Many maintain ties to their rich heritages while they live and work in the today’s world. For more information, please see The Field Museum The Ancient Americas website about Understanding Cultures at www.fieldmuseum.org/ancientamericas/understanding_faq.asp.
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