8th Grade - Physical Science
A. Purpose: The purpose of this experiment is to allow the experimenter to gain a stabilized understanding of the medium through which sound waves travel via two different experiments. The experimenter will establish knowledge about sound waves and physically see the results of those sound waves in motion. Sound waves are an important section of science that is useful for every student to understand. Features of these sound waves will be demonstrated clearly throughout the simple experiment.
While sound waves are often explained to students like waves of the ocean, rolling from one point to another, the reality is that there are, in fact, two kinds of waves. Transverse waves are waves like those found in the ocean, while longitudinal waves are the kind of waves that sound travels by. Many scientist contributed research to this phenomenon, but by far, James Clerk Maxwell's works during the mid-nineteenth century have best demonstrated the conclusion that sound is a longitudinal wave. (Wikipedia) The 1800's were a great time where science thrived in technological advances. (sciencemuseum.org) The question in the mid-1800's, though, was what do sound waves travel through? Or, what is the medium through which sound waves travel? A medium is a substance or object that something such as sound waves or light, can oscillate. For example, when a man is walking down the sidewalk, air is the medium through which he is oscillating, but when the man goes swimming, water is the medium through which he is now traveling.
This experiment hopes to show the results and affects of sound waves in motion. Above all demonstrations will be performed to determine the medium through which those sound waves travel. The student will hopefully gain a better understanding of both sound waves and their consequences. Usefulness of this knowledge is beyond helpful, but almost necessary.
The intelligence of how sound waves oscillate is essential to the young mind's knowledge as a student. Sound waves are an important part of science as a whole and must not be skipped over in the learning process. Understanding of this phenomenon is useful to understanding of many more topics of further study. This topic is of interest to science in many fields.
Hypothesis: If plastic wrap is placed tightly around a bottomless 2-liter plastic bottle, and that bottle is placed upside-down next to a lit candle, and the plastic wrap is gently flicked with one finger, then the flame will go out due to the sound waves exiting the bottle. Furthermore, if plastic wrap is placed tightly over the top of a large glass bowl, and a small amount of rice is poured on top of the plastic wrap, and a pan is held up over the bowl, while a spoon thumps the back of the pan, then the rice will begin to “jump” around due to the sound wave oscillating from the the pan.
1. Plastic wrap
6. Plastic 2-liter bottle
7. Large pot
8. Wooden spoon
9. Large bowl
Procedure for Experiment #1:
1. Cut away the base of the plastic bottle so that there is a big hole at the bottom.
2. Use the plastic wrap to cover the hole that was created when the bottle's base was cut away.
3. Flick the bottom of the bottle to hear the dull thump.
4. Hold the bottle so that the opening from which you drink is pointed toward the experimenter's ear. 5. Flick the plastic wrap again and heat the sound as it comes through the bottle.
6. Light the candle.
7. Hold the bottle so that the opening from which liquid is poured is right at the flame. Try to hold the opening as close to the flame as close as possible without melting it or catching it on fire. When the bottle opening is positioned properly, flick the plastic wrap at the other end so you hear the dull thump.
8. Note the result.
Procedure for Experiment #2:
1. Stretch the plastic wrap over the top (open end) of the large bowl.
2. As was did in previously in the first experiment, make sure the plastic wrap is stretched tightly across the bowl.
3. Spread some rice over the plastic wrap that is stretched across the top of the bowl.
4. Bring the large pot near the bowl, holding it so the top of the pot (the open end) points toward the top of the bowl.
5. Use the large spoon to start banging against the bottom of the pot.
6. Watch the rice.
7. Clean up the mess.
Observations for Experiment #1:
1. Bottom of bottle is cut away easily with large right-handed scissors.
2. Plastic wrap is stretched across open hole at bottom of bottle with ease. Outer edges are somewhat wrinkled.
3. Plastic wrap makes low-pitched, dull thump when gently flicked.
4. Bottle is held up to experimenter's ear with the experimenter's right fingertips. Plastic wrap is flicked. Thump is much louder than before.
5. Candle is lit with match. Experimenter's index finger suffers a moderate burn.
6. Bottle is held up to the fire with the small opening upside-down. Bottle end is approximately ½ in. away from flame.
7. Flame is blown out. Thin stream of smoke rolls from candle tip.
Observations for Experiment #2:
1. Plastic wrap is stretched across bowl with ease. Edges are slightly wrinkled.
2. Plastic wrap is double checked by experimenter. Wrap is extremely tight.
3. Approximately 47 grains of cheap, Kroger brand white rice are spread across wrap.
4. Large black pot is held up 3 inches away from the bowl by experimenter.
5. Large metal spoon is banged consistently against the back of the pot by experimenter. Family of experimenter becomes more or less annoyed.
6. Rice begins to “jump” around on top of wrap.
7. Supplies are put back where experimenter originally found them.
Hypothesis was confirmed. The candle flame was most definitely blown out, an the rice jumped like mexican jumping beans. The reason for both of these results are simple. When the plastic wrap on the bottle was flicked next to the candle, sound waves were created from the vibrations. As these sound waves traveled through the bottle, AIR was pushed out of the bottle, blowing out the candle. Air. Does this mean air is the medium through which sound travels? Yes! The second experiment confirmed this. When the pot was struck with the spoon, sound waves were created by the vibrations, air was pushed away from the pot, blowing the rice, giving the impression that the rice was jumping.
This experiment could not be improved much. The results were easy to recognize and conclusive. The only thing that might possibly be changed is the second experiment. The pan was slightly awkward to hold, and the experimenter had to strike the back quite hard in order for a result to be seen. This mild dilemma can be fixed by using something with a thinner back.
Ideas for future research are difficult to distinguish due to the simplicity of the experiment at hand. Sound waves, it seams, can only be discovered to a certain degree. Although, the pursuit of knowledge should never be underestimated or defined. Future research will always be necessary in order for science to expand it's interests and fields of study.
Rosenoff, Steven. Classroom Lecture. April 12, 2012.
The contributors of Science Museum, “Science and Medicine”.
Wikipedia contributors, “TransverseWaves,” Wikipedia, The Free Encyclopedia
Wile, Dr. Jay L. Exploring Creation with Physical Science, 2nd Edition. Apologia Educational
Ministries, Inc. 2007