Teaching Physics with the Physics Suite Edward F. Redish

The Resonance Simulation

 The PhET simulation team have a simulation that shows a mass on a spring being driven by an oscillating base as shown in the figure at the right. You can access this simulation at http://phet.colorado.edu/en/simulation/resonance. A. Set the parameters of the oscillator as follows: One resonator Mass of resonator, m = 1.0 kg Spring constant, k = 25 N/m Damping constant, b = 0.1 N-s/m. On the palette where you set the oscillator parameters it quotes "frequency = 0.796 Hz." Is this the natural frequency (in cycles/sec = Hz) of the undamped oscillator (with b = 0) or for the damped oscillator? Explain the difference and how you calculated them. B. When you set the driving frequency to be well below this (say f = 0.6 Hz) does the mass oscillate with (in phase) with the driver or opposite to it (out of phase)? What happens when you the the driving frequency above the natural frequency (say f = 1.0 Hz). In phase or out of phase?

C. Using the ruler, find the driving frequency at which the driven oscillator has the largest amplitude and give their values. Is this driving frequency closer to the frequency of the damped or the undamped oscillator?