# NTNUJAVA Virtual Physics Laboratory

## Easy Java Simulations (2001- ) => Ahmed's contribution (EJS simulations) => dynamics => Topic started by: ahmedelshfie on June 08, 2010, 07:10:07 pm

Title: Barton’s Pendulum
Post by: ahmedelshfie on June 08, 2010, 07:10:07 pm
This following applet is Barton’s Pendulum
Created by prof Hwang Modified by Ahmed
Original project Barton’s Pendulum  (http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1598.0)

All objects have a natural frequency of vibration or resonant frequency. If you force a system - in this case a set of pendulums - to oscillate, you get a maximum transfer of energy, i.e. maximum amplitude imparted, when the driving frequency equals the resonant frequency of the driven system. The phase relationship between the driver and driven oscillator is also related by their relative frequencies of oscillation.

Barton’s Pendulum consists of eleven pendulums hanging from a single thread that is connected between the two ends of a wooden rod (figure 1). The thread sags in this asymmetric way because the driver pendulum is a wooden ball 5cm in diameter, and the other ten are inverted Belmont Springs drinking cups. The lengths of the driven pendulums range from 1.0m to 0.1m in 10cm intervals; the driver is 0.5m in length to the center of the ball. When the driver is given a swing, it sets into motion the other ten pendulums, with the result that the 0.5m driven pendulum has the largest amplitude and the other amplitudes being smaller and smaller the further away from the 0.5m they are.

You also get a very clear illustration of the phase of oscillation relative to the driver. The pendulum at resonance is ?/2 behind the driver, all the shorter pendulums are in phase with the driver and all the longer ones are ? out of phase.

You can change the length of the driven pendulum (change ID from 1-10).
Title: Re: Barton’s Pendulum
Post by: ahmedelshfie on June 25, 2010, 09:14:22 pm
A Barton's Pendulums experiment demonstrates the physical phenomenon of resonance and the response of pendulums to vibration at,
Below and above their resonant frequencies. In its simplest construction,
Approximately 10 different pendulums are hung from one common string.
This system vibrates at the resonance frequency of a center pendulum, causing the target pendulum to swing with the maximum amplitude.
The other pendulums to the side do not move as well, thus demonstrating how torquing a pendulum at its resonance frequency is most efficient.
data from  http://en.wikipedia.org/wiki/Barton%27s_Pendulums