The Velocity of Water Ripples

By Emily Schucht, Samantha Yau, and Amanda Thompson

Background

Problem

Hypothesis

Variables

Supplies

Data

Conclusion

Bibliography

Links

Return to Research Page

 

Background Information:

 

            The most common known from of a wave is something that fans do at a football game. However, waves are things that take place everyday. A water wave is a disturbance which moves along a medium from one end to the other (4). This type of wave carries energy and is made up of a crest and a trough (3). Waves move across the water carrying energy, which may have begun through the action of wind, of an object falling into the water, or even the force of gravity, as with tidal movement. If the wave is caused by a disturbance then it only temporarily displaces the particles from their rest position. The wave is an energy transporter, carrying energy from one location to another. There are many different types of waves, but a surface wave is a wave in which the particles of the medium undergo a circular motion. These particles travel in clockwise circles (2). Water waves also require a medium in order to transmit energy, so they cannot transmit through a vacuum. Experiments conducted in a ripple tank with water waves can explain how waves slow down as the water becomes shallower how waves change direction when traveling through another medium, and how waves are reflected from different surfaces(5).

            As for the future of water waves, currently scientists are working on trying to harness wave energy to supply the Earth’s own energy needs (1). For our experiment, we will be testing the velocity of the waves with different amounts of water in the container. We plan to drop a rock into the container at the same height for every trial. In addition, we will record the wave speed with a video camera that will allow us to calculate the wave speed. With this information, we hope to better out understanding of waves, and their characteristics.  

 

 

Statement of Problem:

 

To determine if and what the relationship is between the depth of the water and the speed of the waves created by a disturbance in the water.

 

 

Statement of Hypothesis:

 

If the depth of the water becomes deeper then the speed of the waves will decrease because of the amount of the water in the container.

 

 

Variables:

 

Depth- the distance from the bottom of the container to the surface of the water when the water is not moving.

 

Velocity- The horizontal movement of the crest of the first wave in comparison to time.

 

 

Supplies:

 

·        Child Size Swimming Pool 

·        Rock

·        Hose

·        Meter Stick

·        Video Camera

·        Logger Pro Computer Application     

 

 

Procedure:

 

Step 1- Fill a child size swimming pool with 3cm of water (use a meter stick to measure the amount).

Step 2- Set up a video camera to record the water ripples.

Step 3- Take the rock and drop it 5cm above the water (again use a meter stick to measure).

Step 4- Repeat steps 1-3 for two more trials with the water height at 3cm. Then do five more water increments; each time going up by 3cm. In the end, there should be  six water heights ranging from 3-18cm and three trials for each different water amount.

 

 Data (Excel)

Data File (text)

 

 

Conclusion:

 

            In conclusion, our hypothesis that if the depth of the water becomes deeper then the speed of the waves will decrease because of the amount of the water in the container was only half-correct. This is because what the ripples actually do is form a bell curve, so that the velocity during the lower amounts of water was the same as the velocity during the higher amounts of water. Therefore, the water amounts that were our middle data points were actually, where the peak velocity was. If we were to do this experiment again then we would test at what height the peak velocity occurs and why it occurs at that height.

            During our experiment we also came across problems that resulted in errors such as the child size swimming pool and the rock that we used was not completely flat which may have resulted in the rock not accurately dropping the same way each time. Also as human beings that are impatient by nature we did not always wait for the water to be completely still before the next trial. There also was a shifting of the camera during the filming which affects Logger Pro and the ability to be able to determine where the ripples were in the video and, the placing of the points in the video. In doing this experiment again, we would try to fix these errors by using a flat surface for a container as well as a smooth rock. We would keep the camera at one constant position and have better markings in the video to make it easier to see how fast the ripples are going. From this experiment, we have learned that things do not always go as planned, and the next tiem we get an opportunity to try an experiment like this again we will use this knowledge in perfecting our technique and results.

  Bibliography:

 

  1. Clayton, Bill. “Bay wash: how to make cheap wave power.” New Scientist 156.n2106. (November 1, 1997): 6(1). General Reference Center Gold.
  2. Russell, Dan Dr. “Longitudinal and transverse Wave Motion.” <http:www.kettering.edu/~drussell/Demos/waves/wavemotion.html>
  3. Soule, Karla. “Waves.” Incka Media. 2004-2007. <http://www.physicsplanet.com/articles/waves >
  4. “The Speed of a Wave.” <http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/u1012d.html>
  5. “Waves.” Research Machines pic. 2004. <http://encyclopedia.farlex.com/wave+(physics)>

 

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