Egg Expert

SCIENCE CONCEPT:

Everything has inertia, making it reluctant to move and to stop. This is part of the First Law of Motion discovered by Isaac Newton. The tendency of an object to remain moving at a constant speed or to remain stationery is called inertia.

STUDENT OBJECTIVE:

The student will explore inertia using two eggs, one hard-boiled and the other uncooked.

OVERVIEW:

In this activity, the student will take two identical fresh eggs and hard-boil one. To identify the two eggs, spin each egg in a saucer and then touch the egg to stop it moving and let go. The hard-boiled egg is easy to spin and stops immediately. But the fresh egg is hard to get spinning and it starts moving again after you have stopped it.

PREPARATION TIME:

10 minutes.

LESSON TIME:

10 minutes.

TEACHER PREP:

Gather materials for the experiment. You will need a hard-boiled egg, uncooked egg, and two saucers.

WORDS TO KNOW:

inertia

force

gravity

friction

TEACHER TEXT:

Why do the two eggs respond differently to the same spin in the saucer? The yolk inside a fresh egg floats in the liquid white. Inertia makes the yolk revolve slowly when the shell is spun, and this slows the shell. But the yolk carries on turning when the shell is stopped, causing the egg to start spinning again when released. The hard-boiled egg acts differently because the yolk is held tight in the solid white inside the shell.

Sir Isaac Newton was the first person to really understand motion. His ability to do this was due to his being able to think about what motion would be like without friction and without gravity. Most of the motions we find on earth involve friction. Friction occurs when two surfaces rub against one another. Newton said his ideas about motion were 'built on the shoulders of giants'. One of those giants was Galileo. Galileo realized that without friction, a moving object would continue to move forever. Galileo's idea led Newton to his First Law of Motion.

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Last modified: Tue Mar 24 16:38:45 PST 1998