Warm-Up Exercise 19

Due 12:15 pm, Wed 10 Oct 2012

Physics 123, Fall 2012

Reading assignment: 18.1-18.3

A wave carries energy. When two waves destructively interfere, however, their amplitudes cancel out. Where has the energy gone? (Consider waves on a rope for simplicity.)

In the moment the waves cancel each other out, the individual bits of the rope are still in motion. The wave energy is 100% transverse kinetic energy at that moment.

In a standing wave, what is the difference between the nodes and the antinodes?

The nodes are the places where destructive interference continually occurs--the rope looks like it is not moving. The antinodes are the places where constructive interference occurs the most--the rope moves from the max positive displacement to the max negative.

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