Yes they're experiment results, which had me puzzled for a while!
But then i figured...FRICTION!
the pendulums which were in resonance had less friction than the single pendulum on its own, therefore the systematic error was reduced and the rate exponential decay was less.
Thanks for the...
You have 2 pendulums attached to the same piece of horizontal string.
One pendulum has a large mass, the other is small.
They are both of the same length.
The large pendulum is released from an amplitude and so the small pendulum resonates.
The rate of exponential decay of the large...