Student+2

=**Give Me a Brake**=

Step One: As a team, you will examine the braking process using the materials provided to you. Consider the marble or small ball to be the object in motion which you need to slow, stop, or prevent from moving. Roll the ball through the three tubes provided. One is a stiff PVC pipe, the second is a paper towel roll, and the third is a foam tube used to insulate water pipes. Using your hand, a rubber band, string, or other materials, see if you can prevent the ball from going all the way through the tubes. If you succeed, you'll have applied a brake within the tube. Try to simply slow it down using the materials provided.

Step Two: Answer the questions below

Questions:

1. What advantages did the foam tube have over the other two materials in terms of the ability to slow or stop the rolling ball/marble?

2. Which material do you think would hold up best over time? Why?

3. Which material gave you the greatest control over the speed of the ball traveling through the tube? Why do you think this was?

4. What provides the "force" in your tube experiments? Where is the friction?

5. Which tube material required the least amount of friction to stop the ball/marble? Why do you think this was true?

6. Bicycle rim brake pads are made of a moderately hard plastic, and are sometimes made of leather. Why do you think these materials are preferred?

Give Me a Brake

Student Worksheet: You are the Engineering Team!

Your challenge is to work as a team to devise an improvement in design for a bicycle braking system that will make it brake more smoothly, and therefore more safely. You may work to improve the rim brake, or come up with a completely new design. Propose your ideas and theories as a group. Then, as a team, develop a proposal which you will present to your class.

Step One: Observation 1. Examine how the common rim brake operates…if possible look at one on a working bicycle.

2. Decide -- as a team -- what you want to change in the design to improve bicycle safety. Discuss materials you might use (metals, plastics, foam, leather), whether you think the size of the pads, or the number of pads might impact the performance of the brake, and finally how easy your new brake will be to operate for someone new to bicycling.

3. Draw a sketch of your new braking system on the other side of this paper, and be sure to include a list of the type of materials you'll use in construction. Call out the areas of the design you have changed and explain why your team came up with these ideas, specifically how it will increase safety.

4. Questions:

How do you think your design revisions will impact the manufacturing cost of the brake?

What materials will be used in manufacture? Why did you select these?

What is unique about this design? (two sentences maximum)

How will your new design impact the longevity or functional life of this brake?

4. Present your ideas to your class….pretend they are individuals who are considering funding the manufacture of your new brake system.