Spinning Eggs

Which ones are boiled.

 

 

 

Category - Force & Motion

Key Idea - Inertia

 

Purpose - Use inertia to determine which eggs are boiled and which are raw.
Nature -  Demonstration or Class Practical
Materials -  One raw and one hard boiled egg
Method - 
  1. Mark the eggs so that you can tell the difference.
  2. Give both eggs a spin on and notice which one spins the best.
  3. Spin the hard boiled egg and the put your finger gently on the top to stop it moving.  Just as it stops take your finger off and note what happens.
  4. Try this again with the raw egg and note the difference.
Safety - Nil
Explanation -

The inner contents of a hard boiled egg are solid and in a fixed position.  The contents of a raw egg are free to move about inside the egg.

When you spin the raw the contents resist the spin due to inertia, while the boiled egg, being a solid, spins quite easily.   When you stop the boiled egg the whole egg stops, but the contents of the raw egg keep spinning so causes the egg to begin to rotate again.
Notes - This is demo helps explain why you get dizzy if you are spun around.  In your ear there is a chamber filled with liquid and lined with sensitive hairs .  As you turn your head or body the inertial lag caused liquid moves the hairs which excite a nerve that relays this information to your brain.  When you spin around and around the liquid rotates with your head, but when you stop it keeps spinning, sending signals to you brain that say that you are spinning in spite of what your eyes are telling you.  This causes dizziness.