PBS - Scientific American Frontier:Changing Your Mind

Alan Alda in Scientific American Frontiers


	Hands On, Minds On

	Planetary Problem Solving

	Self Propelled Learning

	Quiz

In the segment, Robot Independence, you observed several robots designed not by humans, but by special computers. At Brandeis University, these computer-designed robots differed widely in appearance and function, but all were able to move across flat terrain under their own power. Do you think you can construct your own self-propelled vehicle? Here's your chance.

OBJECTIVE

In this activity you will build and investigate the rubber band motor. Then, you will use this motor to power a vehicle you create. Through tweaks, tests, and changes, you'll improve the design to attain the most efficient and longest-traveling cart.

This activity page will offer:

experience in the transfer of energy
opportunity to construct self-propelled vehicles
an arena in which to design, create, test, and improve a model
opportunity to construct an understanding of design evolution

MATERIALS

rubber band

thread

spool

metal washer

paper clip

cotton swab

tape

image of spool

PART 1 - A RUBBERBAND MOTOR

PROCEDURE

Insert a rubber band through the hole in the middle of a thread spool. Make sure that the ends of the rubber band stick out from both ends of the spool.

Insert a paper clip through one of the exposed rubber band loops.

Use tape to secure this clip to the side of the spool.

Insert the other exposed end of the rubber band through a metal washer.

Pull the loop through the washer. Then, stick a cotton tipped swab through the loop.

Wind the swab. As you turn it, the rubber band will twist up.

Once enough tension has been wound into the rubber band, place the spool on a flat surface.

Release your hold on the spool and swab. What happens?

Try different variables to see if you can increase the travel distance.

HINT

You may have to tweak your design using a different size spool, larger or smaller rubber band, or strips of sand paper that will increase the friction between the spinning spool and the floor.

QUESTIONS

What happens when you release the wound-up rubber band?

Starting with the sun, describe the energy transfers that occur in order to get the spool moving.

What form of energy is being stored before letting go?

What energy transformation occurs when you let go?

Where does the energy of the spinning spool go?

PART 2 - A SELF PROPELLED VEHICLE

MATERIALS

spool motor you built in part 1

scrap

cardboard

tape

cardboard

scissors

paper clips i

PROCEDURE

Use scissors to cut out a rectangular cardboard frame that is exactly 4 inches wide by 6 inches long.
NOTE: If the class is using metric measurements, the vehicle dimensions should be simplified to 10 cm wide by 15 cm long.

Cut out four circular wheels. The wheels can be any size.

Straighten out one bend in a paper clip to form a shaft. Tape the looped portion of the clip to the cardboard chassis. Make sure that straight piece of the clip projects beyond the side. Slip the wheel over this axle. To keep the wheel from falling off, you may need to bend up the end of the clip or add a hub of clay.

Cut out a window in which to "drop in" you spool engine.

To propel this vehicle, wind up the spool engine.

Drop in the engine and release the spool. What happens?

ENGINEERING AN IMPROVEMENT

Here's your chance to think like an engineer. How would you improve the design of this vehicle to increase the distance it travels? To help define these possibilities, first brainstorm a list of all the different things that you can change. Then, using whatever parts are available, build a racer that will test your thoughts. Keep improving the design until you get a spool that travels the furthest distance.

THINK ABOUT IT

When improving their design, one team used sandpaper to "rough up" the rims of the spool that made contact with the ground. This strategy worked! The spool traveled nearly twice as far. Can you explain why the rough surface was a more efficient wheel than the original spool edge?

EXTENSIONS

Imagine you are in charge of designing three robotic spacecrafts. Each craft will explore the surface of only one planet. Your job is to design a self-propelled craft that can send back data about this alien world. Since cost control is essential, design one craft with special modules that can be adapted for each environment.

The three planetary environments are:

Planet covered by a shallow ocean of water.

Planet with a quick-sand like surface.

Planet with extreme temperature range and hard rock surface.

With a classmate, brainstorm all of the parameters that need to be considered in the development process. Identify what needs are common to each of the three robots. How will can these needs be met with the same module? What special considerations are needed for each robot? How will the robot design be customized for each mission?
Once you have thought out your design, produce the blueprints for these three vehicles.
Using simple art materials, construct one of the three vehicles.
How would you sell your ideas? Present your model and blueprints to your classmates as if they were a panel looking into funding your project.

WEB CONNECTION

Cool robots of the week!
LEGO robots built by University of Edinburgh in Scotland.
MITs robot challenge.

"Hands-On, Minds-On" and "Self-Propelled Learning" were contributed by Michael Dispezio, a Massachusetts-based science writer and author of "Critical Thinking Puzzles" and "Awesome Experiments in Light & Sound" (Sterling Publishing Co., NY).

ANSWERS

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