Perching Parrot
Students explore the concepts of center of mass and static equilibrium by seeing how non-symmetrical objects balance. Using a paper cut-out shape of a parrot sitting on a wire coat hanger, they learn that their parrot exists in stable equilibrium — it returns to its balancing point after being disturbed. The weight of its tail makes the parrot balance upright. Give the parrot a push, and she knocks off balance, but swings back and forth until coming to rest in balance again.
How does a parrot balance on a hanger?Copyright Hauser, 1999.
Engineers verify the safety and robustness of their designs by performing calculations to assure that the structure can withstand the anticipated loads (forces) due to gravity, vibration, pressure, etc. For example, an engineer who designs air conditioning units, ceiling fans or washing machines that continually vibrate must ensure that the support structure is in static equilibrium, and can resist the forces due to the vibration.
After this activity, students should be able to:
- Use a model to illustrate the concepts of equilibrium and center of mass.
- Explain how all forces on an object must cancel out exactly for an object to be stationary.
- Describe how engineers verify the safety and robustness of their designs by performing calculations to assure that the structure can withstand the anticipated loads (forces) due to gravity, vibration, pressure, etc.