Get A Grip!

Using just a shoe, a protractor and a large board, students can get an inside look at the mechanics of friction

Every year I look forward to watching basketball games. During pre-game warmups, players go through various drills to make sure their minds and bodies are ready for intense competition. Some of these drills include pivoting, offensive and defensive movements, evasive maneuvers, hopping, jumping, shuffling, stop-andgo and quick sprints in all directions.

Stepping lively

The shoes basketball players wear must grip the varnished hardwood floors to allow the players to move quickly in all directions.

Oftentimes, loud screeching sounds can be heard throughout the gymnasium. Some fans equate the screeching shoes to a teacher scratching their nails j against a chalkboard. In my opinion, the sounds signify the soles of shoes being tested to their friction limitations.

Every basketball player and referee find ways to assure their soles produce the best friction. Sometimes, they will vigorously rub a wet towel and over the soles of their shoes. Other players wipe sweat off their foreheads with their hands, then rub the soles of their shoes. Throughout the entire game players do whatever is necessary to maintain the best friction between their shoes and the floor.

On the other hand, teaching basketball to my students during P.E. is a very careful experiment because the boys and girls wear the same shoes which they wore to school. As they try basic basketball maneuvers, they slip and slide, fall down, skid several feet and lose control of their bodies.

Making conclusions

In this lesson the purpose is to have students hypothesize, experiment, chart results and draw conclusions about the types of shoes that produce the best friction. Then, after examining various types of shoes, students will determine what kind of materials, texture and sole patterns work best for providing adequate friction for P.E. and everyday activities.

The lesson

Friction is all around us. It can be an unwanted force that degrades performance of machines, cause non-aerodynamic motorized vehicles and airplanes to use more fuels and may prevent a baseball player from sliding all the way to a base.

The rougher the two surfaces are, the more friction is produced. In order to overcome friction, objects must work harder. Since energy doesn't just disappear, it is converted into heat. You can prove this by rubbing your hands together vigorously.

Friction can also be a very useful force. Try sprinting on a wet floor. You definitely need a little friction to get a grip in order to get yourself moving.

Friction always acts in opposition to an object's motion. This was explained by Isaac Newton's First Law of Motion: "An object in motion will remain in motion at a constant velocity unless acted upon by unbalanced forces."

Materials:

* Large protractor

* Various types of shoes

* Water

* Sponge or washcloth

* A board or a cookie sheet (12'' × 20'')

* Ruler

Before starting the experiment, divide the students into groups of four. In each group, one student must place a shoe on the angled surface of the board. Another student must slowly move one end of the board to an angle that causes the shoe to begin its slide. The third and fourth person record the angle and how far the shoe slid.

Procedure:

1 Have students take off their shoes.

2 Each group selects one shoe and places it precisely on the end of the board.

3 Slowly, raise the end where the shoe has been placed.

4 Use a protractor to measure the angle when the shoe starts to slide down the board.

5 Record the angle, measure the distance the shoe slid and place the data onto a chart.

6 Repeat this procedure three times and compute the averages.

7 Wet the surface of the board and repeat steps 3 through 6.

Evaluation:

1 Make sure students are performing the experiments consistently and accurately.

2 Is the traction of a shoe affected by a wet surface?

Extension:

Repeat the experiment, but manipulate the dependent variable with the following:

1 Apply oil onto the board.

2 Place crushed ice under the shoe and place it on the board.

3 Warm the board and the sole of the shoe and place it on the board.

Does oil, ice or heat affect the traction of a shoe?

John Cowens has taught for 26 years. He currently teaches sixth grade at Fleming Middle School in Grants Pass, OR. E-mail: snewoc@yahoo.com

Copyright Early Years, Inc. Feb 2005
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