force Archives - Casa Bouquet

The shoe friction experiment helps children do an activity that has a practical application. You can measure the friction for various types and sizes of shoes with equipment or estimate it by using a board at an incline.

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Instructions for shoe friction experiment

Attach a short piece of rope to one side of an S hook. You will use the other side of the hook to hook the shoes.
Lay the board flat on a table or floor and place a shoe at one end. Slowly begin pulling the shoe until it moves at a steady speed. What do you observe about how hard you have to pull to get the shoe moving and the pull once the shoe is moving?
If using the Dual Range Force sensor, attach the utility handle to one end and set the range to 10N. Attach the force sensor or spring scale to the rope. Repeat the shoe-pulling and record the results. Make a chart in your notebook to record your findings.
Next, place the shoe at one end of the board. Slowly raise the end of the board until the shoe slides down the ramp. Measure the height and the angle.
Try setting up the board and an angle and the shoe with the force sensor or spring scale. Measure the force to pull the shoe down the ramp. How does this compare with pulling the shoe when the board is flat?

Does the weight of the shoe make a difference? Does it make a difference if the sole is wet or dry? Do different shoes move down the incline at different angles?

Why do you need special shoes for different activities? How does friction affect basketball, skateboarding, salsa dancing?

Supplies

Board
Books or blocks to use for incline
Meter stick, protractor
Assorted shoes
Heavy string or rope
S hook or large heavy paperclip
Vernier Dual Range Force Sensor OR
handheld spring scale
paper or notebook for recording results, pen

What is the science?

Content: force, friction, coefficient of friction, motion, Newton’s Laws

A force that opposes motion is friction. Two surfaces rubbing against each other will have some amount of friction. You can have situations with where you might not think about friction, such as sliding across ice (low friction) or wheels rolling on a street (high friction), but there is still friction. To calculate friction, the equation is f = ? x N (friction force equals the coefficient of friction times the Normal force (weight in Newtons if object is perpendicular to the earth’s surface)).

Here is a typical physics force diagram for a block on an inclined plane:

Resource links

http://www.opensourcephysics.org/items/detail.cfm?ID=10081
Block and spring on an inclined plane model from Open Source Physics
http://www.vernier.com/products/sensors/force-sensors/dfs-bta/
Dual range force sensor from Vernier Software & Technology
http://www.vernier.com/products/interfaces/labq2/
LabQuest 2 data collection interface from Vernier Software & Technology
http://www.flinnsci.com/teacher-resources/safety/general-laboratory-safety/
General Lab Safety resources from Flinn Scientific. Be sure to check out the Student Safety Contract.

Let’s talk story

The classic experiment in physics used a wood block with 4 surfaces (such as different sandpapers) to slide on the board. A group of us were teaching college physics to non-majors (sometimes known as physics for poets). We changed the lab to shoe friction experiment and found a big difference in student interest in the experiment. I worked with a group of middle school teachers and introduced this lab. One teacher was the school basketball coach. He had the kids test different shoes, from discount to high-end. The results showed they could get good friction from an economical shoe!

I’ll be looking for comments below, or contact me at lisa [at] thecasabouquet[dot]com.