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Group Visits
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On the first Tuesday during our stay at Canberra, the Einstein group was allowed the privilege of touring the Australian Defence Force Academy. Although the cadets were not on campus, we found the tour quite interesting and delightful. The bulk of our visit was spent in a research lab learning about the mechanics of oceanography. As the name suggests, the area deals with the behaviour of waves in the ocean; information that is of great importance to the navy. The following section of the web page details, in relative simplicity, the main concepts introduced to us during our stay at ADFA.
Waves are generated out at sea as a result of wind, and geographic disturbances at the sea floor. These waves travel, relatively undisturbed, through vast distances to the seashore. Their interaction with the land and shallow areas of the sea determines their effect on ships, and also swimmers and surfers. When a water wave collides and reflects off a barrier, for example the hull of a ship, the reflected wave will have the same frequency and wavelength (and therefore velocity) as the incident wave. When the ‘pulses’ (nodes or antinodes of the waves) are momentarily occupying the same part of the wave, the amplitudes of the individual pulses add together to give the amplitude of the total disturbance of the wave. This effect is known as superposition, as illustrated below. When part of, or the whole of a pulse is ‘cancelled out’ by another, incoming pulse, destructive interference is said to occur. When two pulses add together to give a maximum amplitude, constructive interference occurs. At the node, the wave is observed to not move at all at a single point. Therefore, there appears to be a wave, but it has no direction of motion this is a standing wave.
This type of wave has an adverse affect on the motion of ships. Predicting their occurrence and the maximum amplitude of their motion helps ships to overcome any obscure movements. |
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