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Water Waves

An Overview of the Waves

Last updated date: 23rd Mar 2023
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When we stand on the beach, we observe that water is moving towards shore rolling in and out. These are the water waves. These waves are formed by the movement of wind across a standing body of water on the beach, which creates disturbances and the waves travel in circular paths. The disturbances propagate with wave speed and water molecules remain at the same position. Water waves are surface waves and they are made of a combination of longitudinal and transverse waves. These waves are formed by the interaction of the Earth, the Sun, and the Moon. Water waves have crests and troughs.

What is Wave?

The rise and fall of water caused by friction of the wind on the water surface is called a wave. A wave is a disturbance on the surface of the body which is travelling in a forward direction. This disturbance is in the form of a ridge or a swell. A wave is an up and down distortion on the water surface. Waves can be standing waves or progressive waves. In progressive waves, crest and trough travel at the same speed in the perpendicular direction. In standing waves, there is no progression. The up and down motion of a water wave is simple harmonic motion.

What are Water Waves?

Water waves are surface waves and they are made of a combination of longitudinal and transverse waves. These waves are formed by the interaction of the earth, the Sun, and the Moon. Water waves have crests and troughs. The source of most waves on the sea surface is wind.

Characteristics of water waves are listed below:

• Crest and Trough - The peak of the wave is called as crest and the bottom point of wave is called as trough.

• Wave Amplitude - Half of the wave height is called as amplitude.

• Wave Height - The distance between the crest and trough is wave height.

• Speed - Rate of the wave travelling in water.

• Wave Frequency - The total number of waves passing through a point in one second is called as wave frequency.

• Wavelength - The distance between two crests is known as wavelength.

Types of Waves Ocean

• Wind Waves - These are the most common waves. In these waves, wind transfers a lot of energy when it comes in contact with the water surface. This forms ripples in water. The more substantial the wind, the larger the waves produced.

• Tidal Waves - These waves arise due to gravitational force between the earth and the Moon. The ocean water remains in its place because of the earth’s gravity but the moon's gravity attracts water towards itself. This causes the wave to rise and fall. When the moon is closer to the side of the earth, it is called high tide and on other hand, it is called low tide. Powerful sea waves produced in the ocean are called tides.

• Underwater Explosions - Bigger waves like tsunamis are caused due to underwater explosions or earthquakes in oceans.

There are three types of sea waves - Tsunamis, swell waves, and wind surges. The tide which attains maximum height is called the spring tide.

Difference Between Waves and Tides

1. Due to the force exerted by the wind on the water, waves are produced and tides are produced due to the gravitational effect between the Sun, Moon, and the earth.

2. Waves are generally produced in shallower parts and tides are produced in deeper parts.

3. Waves occur all the time due to wind and tides occur twice a day with a time gap of 12 hours and 35 minutes.

Work of Sea Waves

Erosion and deposition due to sea waves give rise to coastal landforms. Hollow caves on rocks are formed due to waves. These caves are called sea caves. When these caves become bigger due to waves, they are called Sea arches. Steep coast rising vertically above sea water is sea cliff. All these formations happen due to waves.

Interesting Facts

• Waves transport only energy, not matter.

• Water waves are very unusual as they can have different speeds.

• There are two high tides and two low tides each day.

Solved Problems

1. The speed of a wave in a certain medium is 1000m/s. If 3600 waves pass from a certain point in 2 minutes, find the wavelength.

Solution: Given,

Speed of wave $\upsilon = 1000m/s$

Frequency of wave n= 3600waves/2min= 3600waves/120sec = 30 waves/sec

We know that wavelength= $\lambda = \dfrac{\upsilon }{n}$ = 1000/30 = 33.33m

Therefore, wavelength=33.33m

2. Obtain the frequency of the wave if its wavelength is 50m and the speed of the wave is 2500m/s.

Solution: Given,

Wavelength $\lambda$= 50m

Speed of wave= 2500m/s

We know that frequency= $n = \dfrac{\upsilon }{\lambda }$ = 2500/50 = 50 waves/sec.

Summary

The rise and fall of water caused by friction of the wind on the water surface is called a wave. A wave is a disturbance on the surface of the body which is travelling in a forward direction. Water waves are surface waves and they are made of a combination of longitudinal and transverse waves. These waves are formed by the interaction of the earth, the Sun, and the Moon.

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FAQs on Water Waves

1. What is the importance of ocean waves?

Ocean waves are important for weather forecasting and climate modelling and also for coastal communities, offshore industry, and shipping routes. The ebb and flow of waves and the tides are the life forces of the world ocean. Ocean currents affect recreational fishing and recreational navigation for the boats. Ocean waves are a very important component of the Mediterranean environment.

2. What are transverse waves?

Transverse waves are a type of mechanical wave. In these waves, the displacement of a particle is perpendicular to the direction of propagation of the wave. The ripple on the surface of the water is an example of transverse wave. In transverse waves, particles don’t move with the wave. Particles move up and down about their equilibrium position. Electromagnetic waves are transverse waves, waves on the string are also transverse waves, and secondary waves of earthquakes are transverse waves too. The ocean waves are also transverse waves.

3. What are longitudinal waves?

Longitudinal waves are also mechanical waves. In these waves, the displacement of particles is parallel to the direction of the propagation of waves. The longitudinal wave consists of periodic compressions and rarefaction at which the medium expands. Sound waves in the air are examples of longitudinal waves. Primary waves of earthquakes are the transverse waves. Water waves are combinations of transverse and longitudinal waves and Rayleigh surface waves are also a combination of transverse waves and longitudinal waves.