A pendulum, gentlemen, is gravity made visible.
Draw the bob aside and release. It swings; it returns; it swings again. Time one full journey — there and back — and you have its period, T.
T = 2π √(L / g)Notice what the formula does not contain. Not the weight of the bob. Not how far you drew it back. Only the length of the string, and g itself. The clock doesn't care about the mass.
drag the bob to try · slide L · tap the board to chalk a dot