Can you design a better sole?

2021-12-14 09:42:21 By : Mr. Carter Huang

Even with the best winter boots, we often slip and fall on the icy sidewalk. Researchers from the Toronto Rehabilitation Institute noticed this problem and decided to study the resistance of winter boots to wet and slippery conditions. They tested more than 100 pairs of boots on an icy slope and found that only about 10% of the boots allowed the wearer to walk at a 7-degree tilt without slipping.

Check the researcher's data on their website Rate My Treads. "Snowflake scales" indicate the extent to which the boots catch ice. Are you surprised by some untestable shoes on this list?

How do we redesign a shoe that gets a three-snowflake rating on the snowflake level? In this activity, you will study some factors that affect the grip of shoes, and then use your new knowledge to improve the grip of shoes.

Take out at least four different pairs of shoes from the closet. Group them according to their purpose. Pay attention to the diversity of tread patterns and materials. When checking shoes, please consider their purpose. Think about what makes each pair of shoes unique.

In most cases, your shoes are closely connected to the ground, while in other cases, such as when you are walking on ice, your shoes are more likely to slip. What helps your grip on the surface? Whether you are slipping on the terrain or walking easily, it has a lot to do with friction, which is a force that prevents the movement of surfaces in contact with each other.

We encounter friction every day, everywhere. It is one of the forces that slows down the rolling ball and makes the ladder lean against the wall. Usually, we can detect friction by using friction as the energy released as heat. If you rub your hands quickly, you should feel warm. That is caused by friction.

The amount of friction between two objects depends in part on the ease with which their surfaces move relative to each other. This measure is called the coefficient of friction. Try sliding on the wooden floor with socks, and then sliding on the carpet with socks. Did you notice the difference? The coefficient of friction between your socks and the wooden floor and between your socks and the carpet is different.

Generally speaking, when smooth surfaces are in contact with each other, the coefficient of friction is low, indicating slippage. Between rough surfaces, a higher coefficient of friction means better traction.

Which case has a higher coefficient of friction: the cardboard box moves on the asphalt, or the cardboard box moves along the polished wooden floor?

If you say that cardboard boxes on asphalt have a higher coefficient of friction, you are right. Smooth wooden floors have less friction against cardboard boxes, so the coefficient of friction is low.

Even surfaces that look very smooth to the naked eye will appear unusually rough and uneven under a high-power microscope, and friction will occur when we walk past them. This is why you will eventually stop when you slide across the wooden floor in your socks!

Listen to the audio clip below. Here, physicist Robert Kapik describes why ice slips.

As Carpick said, the surface of ice is very different from other familiar surfaces. Scientists believe that the reason why the ice becomes slippery is that there is a tiny layer of water on the surface.

Recall the scene of you sliding on a smooth wooden floor wearing socks. Now imagine adding marbles under your feet. They make the wood slippery, right? Those marbles are a bit like a liquid layer on the ice.

The slip coefficient between the shoe and the ice requires some special design considerations. Let's take a look at the shoes worn by curlers, climbers, aboriginals and other people who have been active on the ice for a long time. While viewing the image, record the observation results of each pair of shoes (ie tread, material) on a piece of paper.

(Source: Rebecca Siegel, from Flickr/CC BY 2.0)

Curling shoes. Curling is a sport on ice, where the team slides a flat rock towards the mark. Learn more about curling and curling.

(Source: Derek Hatfield, from Flickr/CC BY 2.0)

Inuit mukluk boots. Pay special attention to the soles.

(Photo taken by Ansgar Walk, from Wikimedia Commons/CC BY-SA 2.5. Shoes courtesy of Rachel Uyarasuk of Igloolik, Nunavut, Canada.)

Now, let us return to the research done by the Toronto researchers. Looking at the list of tested shoes and their performance, is there anything surprising or worrying from a consumer's point of view?

(Video provided by Toronto Rehabilitation Institute-University Health Network)

Let's explore the adaptability that some animals have evolved to sail on smooth ice. While viewing the image, add observations below your shoe annotations. Consider the following questions:

Polar bears spend a lot of time on the ice and have evolved some cool characteristics to prevent them from slipping. For example, their large claws are up to a foot long, allowing them to make more contact with the ice surface. Between their toes, tufts of hair stick out from inside to contact the ice cubes, helping to prevent slipping. Their hind paws are covered with tiny bumps to provide extra grip.

(Source: Peter Halling Hilborg, from Flickr/CC BY 2.0)

If you look closely at the feet of these gentoo penguins, you will find that their toes are bumpy and ribbed. These features provide grip on smooth ice. When they walk on land, the claws at the ends of their toes help them grasp the cold surface.

(Source: Pablo Fernicola, from Flickr/CC BY-NC 2.0)

Adult harp seals spend a lot of time in the water, while juvenile seals spend a lot of time on land. Their claws are covered with fur, and they have sharp claws that can move more easily on ice.

(Source: CaroLa, from Flickr/CC BY 2.0)

In a test conducted by the Toronto team for Rate My Treads, only 9 of the nearly 100 boots can handle a 7-degree tilt without slipping. You will perform two tests to determine how the sole material and tread surface area affect friction on ice. You will then use your data to redesign or adjust the sole to improve its grip on the ice.

In the next investigation, you will use three different types of materials to cover shoe print cuts. Then, you will test the gripping ability of each model on the wooden ramp by calculating the speed at which the wooden ramp falls.

— Which material makes the model move the fastest?

— Which material causes the model to move the slowest?

— Based on your data, how does each material you test affect friction?

Remember, slower speeds indicate increased friction.

In this survey, you will apply three tread patterns with different surface areas to shoe print cutting. Once again, you will test the ability of each model to grasp the wooden ramp by calculating the speed at which it slides down.

How do you ensure that your design represents three different surface areas?

— Which model is the fastest?

— Which model has the slowest driving speed?

— Based on your data, can you make a general observation of the relationship between tread surface area and friction?

Now that you have studied the effect of sole material and tread surface area on shoe grip, you can use your data to help you create a winter shoe (or boot) design that can grab the ice surface instead of making you roll.

You need to prepare the ice ramp at least one full day before the test. Find a large tray or shallow container that is at least 18 inches long. Fill the tray with water and freeze for at least 24 hours. The deeper the tray, the longer the water will freeze. On the day of the test, remove the tray from the refrigerator and use a protractor to support it on common household materials (such as marker cases, notebooks, or books) at an angle of 7 degrees.

First, you will test the grip of your unmodified shoes on an ice ramp. The supporting ice is inclined at seven degrees. For each test, follow the steps of the test protocol below.

It is important to use the same weight in each test.

Install the spring scale on the shoe. This can be done in many ways, but the hooks on the spring balance can easily pass through the laces or mesh.

Place the shoes on the icy surface. The heel of the shoe should be placed at the lowest point, ready to lean upward.

Pull up the shoe and incline it seven degrees. It only takes a few inches to provide data.

Record the force (in Newtons) required to pull the shoe. Determine the force by reading the indicator line on the spring scale.

Print. Color the sole of the shoe and press it on the graph paper. Calculate the painted squares to estimate the surface area of ​​the tread in contact with the ice, and record this number on your engineering design plan worksheet.

Using common classroom or household materials, redesign the sole to increase friction and the force required to pull it. Your modification must not add more than one inch to the height of the shoe, and it must not be larger than the sole. Use data from shoe sole materials and tread surface area surveys to guide your design process.

Brainstorm ideas by sketching out your design ideas on the engineering design worksheet. Think boldly and be creative!

— What are the reproducible qualities of shoes designed for ice?

— Think about the results of your tests on shoe sole materials and tread surface area. Can you mix and match the designs you come up with?

——What will the bottom of these shoes look like?

— How much of the shoes will come into contact with ice?

Choose the best design elements from the brainstorm and draw them into blueprints for making shoes. Your blueprint should include a cross-sectional view of the sole in contact with the ice and a view of the tread pattern.

— Which elements of the design do you think can improve the grip of your shoes on ice?

— How does your design draw on your previous shoe sole material and tread surface area tests?

— Explain what you want to see on a micro level when this newly designed tread comes into contact with ice.

Use the materials and blueprints of your choice to create your new sole.

Follow the test protocol you used to test the unmodified shoes. Record your results on the engineering design worksheet.

Want to continue to improve your design? Try to change one feature at a time, and test each change to see how it affects the interaction between the sole and the ice. Keep track of the changes you make on the engineering design worksheet. Which changes have the biggest impact on the shoe's grip on ice?

Create a mini poster presentation of your design and share it with your classmates. In your presentation, include your graphic data, prototypes and surface tread prints.

Now that you have designed your shoes, let us see how your findings differ from the research results collected by Toronto scientists. The researcher who led the team, Barry Westhead, described the progress of the shoe design and the materials that scientists are currently testing.

— Does your design reflect any characteristics of today's cutting-edge design?

— Now that you are familiar with the content currently being studied by shoe designers and researchers, how will you further modify your design?

— What restrictions do you have that a real shoe designer would not have?

— How is your design used in shoes developed by experts?

MS-ETS1-1. Defining the standards and constraints of the design problem with sufficient precision to ensure a successful solution, while considering the relevant scientific principles and the potential impact of possible solutions on people and the natural environment that may limit possible solutions.

MS-ETS1-2. Use system processes to evaluate competing design solutions to determine the extent to which they meet the criteria and constraints of the problem.

MS-ETS1-4. Develop a model to generate data for iterative testing and modification of proposed objects, tools, or processes to achieve the best design.

SEP: Ask questions and define problems, construct explanations and design solutions

DCI: PS2.A: force and movement, PS2.B: interaction type

CCC: Causality, Stability and Change

The impact of science, engineering and technology on society and the natural world

MP.2 Reasoning abstractly and quantitatively.

SL.8.5 Include multimedia components and visual displays in the presentation to clarify statements and findings and emphasize the main points.

WHST.6-8.7 Conduct a short research project to answer a question (including a self-generated question), use multiple sources and generate additional relevant and focused questions, allowing multiple exploration avenues.

Teachers who test this resource on the spot have the following suggestions for teachers who use this resource: Sri from New Jersey said: Make sure students record data in the first two activities and motivate them to use the data in the third (final) activity. Discuss with students why they think their design works in a specific way. If they were given a second chance, what would they modify? why?

Brienne May is a special education teacher in Pittsburgh, Pennsylvania. Her favorite lessons can inspire children to solve real-world problems (such as her SciFri resources!); participate in scientific debates; and get their hands dirty through activities such as gardening, engineering projects, and animal anatomy.

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