Inertia

So You Want to Do a Project about Inertia!

Purpose

To demonstrate how inertia affects the motion of an object.

Materials

• Small raw egg
• Timer
• Helper

Procedure

CAUTION: After handling raw eggs, wash your hands and any materials touched by the eggs. Raw eggs can contain harmful bacteria.

Record the time in a Raw Egg Spin Data table like the one shown.

1. Place the egg on a table. Once the egg is stationary, watch it for several seconds.
2. Give the egg a gentle spin and then release it. Observe its motion.
3. Spin the egg again and ask a helper to time the spin. When you say "go," your helper will start timing and you will start the egg spinning.
4. Repeat step 4 three times. Make an effort to spin the egg with the same amount of force for each test. Average the spin times of the four tests.

Results

The egg wobbles as it spins, then stops. The average spin time will vary.

Why?

The egg continues to spin after it is released because of inertia. Inertia is the resistance an object has to any change in motion. It is the tendency of a nonmoving object not to move and of a moving object to continue to move unless acted on by some outside force. The material inside the shell of the raw egg affects the way the egg spins. When force is applied to the solid shell of the egg, the shell begins to move. But due to inertia, the liquid yolk and egg white inside do not start spinning as soon as the shell does. The force of the moving shell on the liquid inside causes the liquid to move, but slowly. The sluggishly moving liquid hits against the inside of the shell, causing the egg to wobble. The wobble reduces the spin time of the egg.

For Further Investigation

Hard-boiled eggs are solid throughout. Would a hard-boiled egg spin longer than a raw egg? A project question might be, How does the phase of matter of an object affect its motion?

Clues for Your Investigation

1. Repeat the investigation with a hard-boiled egg.
2. To distinguish the eggs, mark an X on the hard-boiled egg.
3. A series of diagrams representing timelapse photography of each egg with arrows representing the motion of the eggs can be used as part of your display. The diagrams placed side by side show when each egg stops spinning in relation to the other.

References and Project Books

• Ardley, Neil. The Science Book of Motion. New York: Harcourt Brace Jovanovich, 1992.
• Churchill, E. Richard. 365 Simple Science Experiments with Everyday Materials. New York: Black Dog & Leventhal,1997.
• Gardner, Robert. Experiments with Motion. Springfield, N.J.: Enslow, 1995.
• Hann, Judith. How Science Works. Pleasantville, N.Y.: Reader's Digest, 1991.
• Kerrod, Robin. Book of Science. New York: Simon & Schuster, 1991.
• Potter, Jean. Science in Seconds with Toys. New York: Wiley, 1998.
• VanCleave, Janice.]anice VanCleave's Physics for Every Kid. New York: Wiley, 1991.
• Wood, Robert W. Mechanics Fundamentals: Fantastic Science Activities for Kids. New York: Learning Triangle Press, 1997.

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