# Why does a stationary wave form at a free end of a water tank?

• songoku
In summary, the conversation discusses the production of stationary waves through the use of an oscillator and a tank. The incoming and reflected waves superpose to create a stationary wave, with an antinode formed at the free end of the tank due to the transverse nature of water waves. This is in contrast to longitudinal waves, such as sound waves, where a node is formed at the end of a closed pipe.
songoku

This is the set up to produce stationary wave. The oscillator on the left will produce wave on water surface then this wave will travel to right, reflected at the tank and the incoming and reflected wave will superpose to form stationary wave.

My teacher said when the water wave hits the tank at the right side, antinode of stationary wave will be formed because it is a free end. I don't understand why it is a free end, I thought it as a fixed end since the tank is a rigid container. My analogy is at the closed end of a closed pipe, node is always formed, not antinode so why at the tank an antinode is formed?

Thanks

songoku said:
My analogy is at the closed end of a closed pipe, node is always formed, not antinode so why at the tank an antinode is formed?
This is the difference between a transverse wave and longitudinal one.

Water waves are transverse; the water level moves up and down while the wave propagates sideways and at the edge of the tank the water is free to move up and down.

Sound waves are longitudinal; the air moves back and forth and at the end of the closed pipe is constrained not to be able to move.

Last edited:
songoku
Thank you very much Nugatory

## 1. What is a stationary wave in a water tank?

A stationary wave in a water tank is a phenomenon that occurs when two waves with the same frequency and amplitude travel in opposite directions and interfere with each other, resulting in a pattern of nodes and antinodes that appear to be standing still.

## 2. How is a stationary wave created in a water tank?

A stationary wave is created by setting up a water tank with a source of waves, such as a vibrating rod, at one end. The waves travel across the tank and reflect off the other end, causing interference and resulting in the formation of a stationary wave.

## 3. What factors affect the formation of a stationary wave in a water tank?

The factors that affect the formation of a stationary wave in a water tank include the frequency and amplitude of the waves, the length of the tank, and the speed of the waves in the medium.

## 4. What is the significance of stationary waves in a water tank?

Stationary waves in a water tank have several practical applications, such as in musical instruments, where they produce specific resonant frequencies, and in engineering, where they can be used to test the strength of structures.

## 5. How can the nodes and antinodes of a stationary wave in a water tank be visualized?

The nodes and antinodes of a stationary wave in a water tank can be visualized using a stroboscope, which creates the illusion of stillness by flashing a light at the same frequency as the waves. This allows for the nodes and antinodes to be seen as fixed points in the tank.

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