Can a Toy Car Reveal the Strength of a Magnet?

Talk It Over

What happens when the like poles of two magnets come close to each other? How could you use their interaction to move a toy car? Would the distance moved tell us anything about the strength of the magnet's force?

Get

• Ruler (metric)
• Access to a photocopier
• Tape
• Small, plastic toy car
• Small bar magnets, 4 or more*

Go

1. Make a photocopy of the ruler. Tape it to the table.
2. Tape a small bar magnet to the top of a toy car.
3. Set the car at the 0 cm point on the ruled paper, like this:

   

4. Bring an end of one small bar magnet near the magnet on the car. If the car moves toward you, reverse the ends of the magnet in your hand. You want the car to move away from you.
5. When you find the correct end, bring the magnet toward the car slowly, stopping when the car begins to move. Measure how far the car moved. Here's an example:

   

6. Repeat step 5 twice more. Average your results:

   

7. Put 2 of the small bar magnets together to make a single, longer bar. Repeat steps 4–6.
8. Put 3 of the small bar magnets together to make a single, longer bar. Repeat steps 4–6.

Stay Safe

There's nothing dangerous in this experiment, but keep your magnets away from compasses, computers, and CDs. Magnets can erase data and distort compass readings.

Go Easy

You can do without measuring if you want. Just demonstrate how you can make the toy car move toward and away from you.

Go Far

The toy car moves away from the magnet because the same poles (north-north or south-south) of bar magnets repel each other. This repulsive force helps run magnetic levitation (maglev for short) trains. A repulsive magnetic force keeps the train suspended in the air above its track. Attractive and repulsive forces generated by electromagnets move the train forward. Because maglev trains don't touch the track, their friction is lower, so their energy consumption and noise levels are lower, too. Maglev trains are being used and evaluated in Japan and Germany. Find out about maglev trains and present information on them in your project. Invent a way to demonstrate the principles that keeps maglev trains suspended or moving forward. A good place to start is with the toy called a Levitron. Read more about it at www.levitron.com.

Show Your Results

Put distances in a data table like this for "Go":

Make a bar graph of the average distances to answer the following question: Does a longer magnet make the car travel farther?

For "Go Easy," draw pictures to show what makes the car move toward or away from you.

For "Go Far," use models, data tables, and graphs to demonstrate how maglev trains work. Include information on maglev technology in your display.

Tips and Tricks

• Don't use a toy car made of steel for this experiment. It will be attracted to the magnet and spoil your measurements.
• When bringing your magnet near the car, make sure you are always in a straight line. Coming in at an angle will affect how far the car moves.

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CliffsNotes Parent's Crash Course Elementary School Science Fair Projects
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