# Barton's Pendulums - Energy Conservation

1. Jun 23, 2009

### wavingerwin

Suppose we have two pendulums of equal natural frequency set up like a Barton's pendulums system (hung on a common string).

If we oscillate one of the pendulums, the other will also oscillate due to resonance.

Supposing it's an ideal system where there is no friction.

If we release the first pendulum at amplitude=A, as the second pendulum starts to oscillate will the amplitude decreases? (this is my guess, since the total energy of the first pendulum will be transferred overtime to make the second one oscillate).

Or will it stay the same, and ultimately both of the pendulum swings at amplitude=A?

Thank you

2. Jun 23, 2009

### Bob S

Energy is transferred back and forth between the two pendulums while the total energy is conserved. Thus the amplitude A is not conserved. A friend of mine built a full size Grandfarher clock, with a long pendulum and a hanging weights on a chain to provide power to the mechanism. He asked me to come over to his house and look at it, because sometimes the hanging weight would sometimes start to swing in unison with the pendulum when their lengths were about the same. The problem was that the clock was sitting on a high pile carpet, that allowed the two hanging weights to couple.