How Fast Is Grandfather Clock Pendulum?

A grandfather clock pendulum reaches about 0.5 metres per second at the bottom of its swing. Its period — exactly one second per swing — depends only on the length of the rod, never on the weight of the bob.

Galileo discovered the constant-period property of pendulums in 1583 by watching a chandelier sway during a service in Pisa Cathedral — using his own pulse to time it.

• Same pace as an escalator
• Period set by length, not by weight