Can a water jet zigzag, standstill or creep back into the hose?


In this video we see a weird water jet. The jet forms a sharp zigzag shape. Some water drops seem to stand still in middle air or even reverse their direction against the forces of gravity! All needed to do this is a speaker, a vibration device and a water hose. How does it work? For an explanation see below the video.

How does the water get such a crazy shape?

Or isn’t this shape that weird at all?Think of what happens when you leave a water hose lying loose when you open the tap: the hose makes squiggly movements when the water pours out of its opening (action = reaction). The direction of the water jet now  follows the movements of the hose in a rotating pattern. You can find many Tom & Jerry cartoons ​​where a loose hose plays the lead role. The same happens in this video. Instead of having a loose hose, the hose is attached to a speaker. The speaker amplifies the movement of the vibration device. As a result the hose and the jet make a circular motion. When watching from the right angle a spiral or a corkscrew shape will be visible.

Zigzag-form

In the video we see a zigzag shape with sharp corners, not a corkscrew shape! How about this then? Well, a perfect spiral will show itself as a zigzag when viewed from the side . Take for example a ballpoint pen spring or a slinky. These are both is a spirals. Now take a spring, each end in either hand, stretch your arms so that the spring is stretched in a vertical direction. Now look! You see …… the same as in the movie, a zigzag . And yet, we know the shape of the spring is spiral !

Stand still of go back

In the video we see a mentioning of a frequency of 24 Hz. This means that there will be 24 vibrations per second, one vibration makes the jet go round one time. We humans can see around 24 Hz, so we can distinguish between  24 video images (frame) per second. At a frequency of 24 Hz, the water jet is back at the starting point each time we see the next image of a round. The jet seems to stand still. Now we can play a bit and change the frequency. We will see that the jet is now before of after the starting point of the earlier image. In this way we are tricked to “see” that the jet streams forward or backwards. We also know this phenomena from the turning wheels of cars. Next time check the turning direction when cars pull up from the traffic lights.

 

WatchingPhysics.net: Watching physics and science videos to enjoy for yourself or to show to your students. Fascinating – Inspiring – Understandable.

 

 

 

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