The following youtube video shows 5 metronomes which oscillate with random phases and which are uncoupled, since no energy or information flows from one to another, so they cannot "know" each other. The metronome needles are at same speed, but started one after the other.
Then someone lifts the metronomes (standing on a board) on a pair of cans. Now we have coupled the metronomes. The cans move a little bit What happens next is that there is a transfer of angular momentum between the cans and the needles. Hence the transfer of angular momentum is the damping force and this is an example of damped harmonic oscillation.
You might find this page at scholarpedia interesting.
