Purpose
To demonstrate the simple harmonic motion of a mass on a string (suspended from a fixed pivot point).

Description
Using a "massless" string to suspend a simple steel ball, set a pendulum bob into motion.
VARIATIONS:
- Use the bowling ball pendulum in large classrooms. Student will be able to better observe the "zero" motion at the pendulum’s maximum displacements.
- To aid in the discussion of simple harmonic motion use a strong light source (slide projector without its lens?) to project the swinging bob's shadow onto the classroom board. Equilibrium, maximum, & minimum points can then be drawn on the board and the motion better studied. Note: make sure bob's motion stays on a plane parallel to the board
- Conservation of Energy Illustration: Add a "stop" (a second fixed rod) in the path of the bob's string. Challenge students to predict what will happen when the bob is released and the bob’s string comes into contact with the "stop". They will observe that the bob will rise to the same height on the opposite side of its swing. Using shadow projection, this demo variation can be quite effective in illustrating conservation of energy.

Equipment
Pendulum Bob
Support Equipment
Ring Stand