Friction with the bottom causes the trough of the wave to disappear, the crest to slow its movement, and when the depth causes the wave height to become 1. Swell: Wind-generated waves that have travelled out of their generating area. Swells characteristically exhibit smoother, more regular, and uniform crests and a longer wave length than wind waves. Toggle navigation. Wave Crest: The highest part of a wave.
Wave Trough: The lowest part of a wave. Wave Height: The vertical distance between the wave trough and the wave crest. There are four basic types of breaking waves: spilling, plunging, collapsing, and surging. Spilling waves are gentle waves with crests that break softly towards the shore. These waves break when the ocean floor has a gradual slope.
Plunging waves break when the ocean floor is steep or has sudden depth changes. A single back-and-forth vibration of the first coil of a slinky introduces a pulse into the slinky. But the act of continually vibrating the first coil with a back-and-forth motion in periodic fashion introduces a wave into the slinky.
Suppose that a hand holding the first coil of a slinky is moved back-and-forth two complete cycles in one second. The frequency of a wave refers to how often the particles of the medium vibrate when a wave passes through the medium. Frequency is a part of our common, everyday language. For example, it is not uncommon to hear a question like "How frequently do you mow the lawn during the summer months?
If a coil of slinky makes 2 vibrational cycles in one second, then the frequency is 2 Hz. If a coil of slinky makes 3 vibrational cycles in one second, then the frequency is 3 Hz. The quantity frequency is often confused with the quantity period. Period refers to the time that it takes to do something. When an event occurs repeatedly, then we say that the event is periodic and refer to the time for the event to repeat itself as the period. The period of a wave is the time for a particle on a medium to make one complete vibrational cycle.
Period, being a time, is measured in units of time such as seconds, hours, days or years. The period of orbit for the Earth around the Sun is approximately days; it takes days for the Earth to complete a cycle. The period of a typical class at a high school might be 55 minutes; every 55 minutes a class cycle begins 50 minutes for class and 5 minutes for passing time means that a class begins every 55 minutes.
The period for the minute hand on a clock is seconds 60 minutes ; it takes the minute hand seconds to complete one cycle around the clock. Frequency and period are distinctly different, yet related, quantities. Frequency refers to how often something happens. Period refers to the time it takes something to happen.
Frequency is a rate quantity. Period is a time quantity. As an example of the distinction and the relatedness of frequency and period, consider a woodpecker that drums upon a tree at a periodic rate. If the woodpecker drums upon a tree 2 times in one second, then the frequency is 2 Hz. Each drum must endure for one-half a second, so the period is 0.
If the woodpecker drums upon a tree 4 times in one second, then the frequency is 4 Hz; each drum must endure for one-fourth a second, so the period is 0. If the woodpecker drums upon a tree 5 times in one second, then the frequency is 5 Hz; each drum must endure for one-fifth a second, so the period is 0. So bigger frequency, smaller period. Conversely, smaller frequency, bigger period.
Another thing that I've seen a lot of the tests ask, if I double the frequency what happens to the period? Well, that's really easy, because I've got a 2 here, doubling the frequency, but I need the product to remain the same. So I got to put a one half there. So if I double the frequency, I cut the period in half. Conversely, if I cut the frequency in half I double the period.
Real real real simple but sometimes students don't notice how that goes and how easy it is until they've seen an example. One other important property about frequency and period which will come up a lot later on in later studies of periodic waves is that period and frequncy can't change.
And that's actually the wonderful thing about period and frequency. Because other properties of the wave will change. If I go like if I've got light coming in and it hits a piece of glass, a lot of its properties will change but its frequency and period can't. Well, it's real simple. If you got 3 waves coming in per second, you got to have 3 waves going out per second.
Because otherwise the waves are going to congregate at the boundary and the boundary can't take that. So frequency and period can be used to characterize a wave as it travels through whatever it's going to travel through. No matter what happens to it, frequency and period remain the same. And that's frequency and period. All Physics videos Unit Vibration and Waves. Previous Unit Solids, Liquids and Gases.
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