In-class group activity 1

Use an on-line simulation from the University of Colorado PhET group to explore the behavior of waves on a string.  Link to the simulation: http://phet.colorado.edu/en/simulation/wave-on-a-string.  Click "Run Now!".

(a) Explore the interface.  Try the different controls and click "Help" to discover features you otherwise may miss.

Open a Microsoft Word document to keep a log of your results and conclusions.   

(b) Investigate the behavior of a wave pulse.

• Start with the following settings:
  • Pulse
  • No End
  • Amplitude: 50 (arb. units)
  • Pulse Width: 50 (arb. units)
  • Damping: 0
  • Tension: high
  • Ruler and timer: checked
• Observe this pulse and measure its speed in cm/s.   
• Vary (one at a time) amplitude, pulse width, damping, and tension, and describe what happens.   
• Return to the original pulse but change the end to a loose end and the to a fixed end and describe what happens.   

(c) Investigate the behavior of a traveling wave.

• Start with the following settings:
  • Oscillate
  • No End
  • Amplitude: 50 (arb. units)
  • Frequency: 50 (arb. units)
  • Damping: 0
  • Tension: high
  • Ruler and timer: checked
• Observe this wave (wave 1).  Describe your observations.   
  • Measure the amplitude of the wave in cm.   
  • Measure the wavelength in cm.   
  • Measure the period in s.   
  • Find the speed of the wave in cm/s.   

• Move the amplitude slider to 25 (wave 2) and then to 75 (wave 3), and describe what changes.   
• With the amplitude slider at 50, move the frequency slider to 25 (wave 4) and then to 75 (wave 5), and describe what changes.   
• Discuss the relationships between wavelength and frequency, period and frequency, amplitude and frequency and speed and frequency.   
• Can you change the speed of the wave?  What can you do to produce a wave that moves with approximately 1/4 the speed of wave 1.   
• Describe what happens when you include damping.