Exploration 17.3: Traveling Pulses and Barriers

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A string can be approximated by many connected particles as shown in the animations (position is given in meters and time is given in seconds).  Restart.  This Exploration considers a pulse on a string and looks at the motion of the individual particles that make up such a string.  Pulse 1 shows a Gaussian pulse incident from the left, while Pulse 2 shows a Gaussian pulse incident from the right.  Notice how the particles never really move in the x direction, yet the information in the pulse does travel across the screen.

In the other two animations the pulse is incident from the left and hits either a Hard or a Soft barrier. The hard-barrier example is depicted by the hand that represents a string whose end is tied down; the soft-barrier example represents a string with one end free to move in the y direction only. 

1. During the hard-barrier example, what is the direction of the force that is exerted on the hand?
2. During the hard-barrier example, what is the direction of the force that is exerted on the string?
3. Describe the differences between the waves reflected at the two barriers (Hard or Soft ).  Explain those differences.

Illustration authored by Morten Brydensholt, Wolfgang Christian, and Mario Belloni.
Script authored by Morten Brydensholt, Wolfgang Christian, and Mario Belloni.
© 2004 by Prentice-Hall, Inc. A Pearson Company