Use eggs to find out about momentum and changing direction. The fresh egg will start to spin again when the finger is released, while the other will remain at a dead stop. The fresh egg has egg fluid and yolk inside it which gains momentum. When the egg is momentarily stopped, the yolk continues to turn inside the shell. When it is released, the viscosity of the fluid between the still spinning yolk and the shell causes the shell to spin again.
Inertia is the tendency of a moving object to remain moving or a stopped object to remain stopped. In engineering, flywheels are big, heavy wheels that are spun to gain inertia. The energy is stored and released to smooth out the operation of engines that have a short burst of power during their running cycle.
- One hardboiled egg
- One fresh egg – the fresher the better
Spin each egg, one hard boiled and one fresh, on a table.
Leave it to spin for a few seconds then momentarily stop it by placing your finger on top.
Release the egg and observe what happens next.