Professor Walter Lewin demonstrates that the period of a pendulum is independent of the mass hanging from the pendulum. This demonstration can be viewed on the video of Lecture 10. (Image courtesy of Markos Hankin, Physics Department Lecture Demonstration Group).

to see the lecture, etc. go to:    http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/video-lectures/