PURPOSE: To show how resonance occurs when the frequency of the driver matches the natural frequency of the system.
DESCRIPTION: A bowling hangs from a cable mounted in the ceiling. Push the bowling ball exactly like a parent pushes a child in a swing. With very small pumping at the resonant frequency the pendulum can easily obtain very large amplitudes.
The above photo's only purpose is to show the bowling ball that serves as the mass for the pendulum. The photo does not show the actual pendulum arrangment. Note that this demo is EXTREMELY DANGEROUS and can cause harm if one is careless enough to give the bowling ball a large push and get hit by it. Do not let students toy with it.
If you take enough care and practice to synch each push accurately, then you can dramatically show that it takes very little force to build large amplitude oscillations.
EQUIPMENT: Bowling Ball.
SETUP NOTES: The bowling ball is stored in the mechanics shelf. Advance notice is required on this demo because it involves bringing in a large ladder to hang the pendulum cable from the ceiling eyehook.
Updated by Jun Qi in 3/24/2000