A Portable Dryer Utilizing the RPM and Centrifugal Force of a Spinning Button Toy
Introduction
The *spinning button toy* is a traditional game enjoyed not only in Korea but also in countries like Canada and the United States. Made from paper and string, it produces a sound similar to wind when spun. Depending on the spinning speed, the toy creates a wide range of sounds, from low to high-pitched tones, akin to the sound of a car engine. The RPM (revolutions per minute) displayed on a car's dashboard indicates how many times the engine spins in a minute. As the RPM increases, the engine sound becomes higher-pitched. In Formula 1 race cars, the RPM can reach an astonishing 17,000, producing a very high-pitched sound. Similarly, the *spinning button toy* produces different tones based on its spinning speed, with a maximum RPM reaching 125,000 to 200,000, which is surprisingly high.
This principle of rapid spinning and centrifugal force can be applied in various practical ways. For instance, a very cost-effective and efficient blood centrifuge has been developed using the same principle. One everyday application of centrifugal force is in a washing machine's spin dryer. Thus, the purpose of this study is to:
1) Analyze the characteristics observed when spinning the button toy;
2) Investigate how to create a button toy that produces the highest-pitched sound and understand the reasons behind it;
3) Apply the principle of the spinning button toy to create a portable dryer.
Research Questions
1. What characteristics can be observed when the button toy spins?
2. What factors influence the pitch of the sound produced by the spinning button toy, and how can these be tested?
3. How can we create a button toy that produces the highest sound, and why does it create the highest-pitched sound?
4. How can the principles of the spinning button toy be applied to create a portable dryer?
Hypothesis
The pitch of the sound produced by the button toy is dependent on its RPM. The higher the RPM, the higher the pitch of the sound. The RPM is expected to be affected by the size of the disc, the distance between the two holes on the disc, and the thickness of the disc.
Method
Making the Observation Button Toy
Following instructions available on the internet, a button toy was made for observation. The characteristics observed while spinning the toy were recorded.
Creating Experimental Button Toys
The disc of the button toy was made from cardboard, and cotton string was used for the string (as a controlled variable). To maintain consistency, all discs were cut from the same cardboard, with two radii of 5 cm and 10 cm, and the distance between the two holes was either 1 cm or 2 cm. The string length was standardized to 140 cm, based on the length that provided the most stable and easy spinning in the observation toy. The handles were made from wooden chopsticks and taped securely in place.
In total, four button toys were created and labeled as follows:
- D1R5: 1 cm between holes, 5 cm disc radius
- D2R5: 2 cm between holes, 5 cm disc radius
- D1R10: 1 cm between holes, 10 cm disc radius
- D2R10: 2 cm between holes, 10 cm disc radius
Measuring the Sound of the Button Toy
A smartphone app available on the iOS App Store was used to measure the pitch of the sound produced when the button toy was spun. Each of the four button toys was spun three times by the same person (Yoon Jinwoo), and the average sound level (in dB) was recorded. The experiment was conducted in a quiet bathroom to avoid background noise.
The toy that produced the highest sound was identified based on the average results.
Evaluating Different Conditions of Button Toys
Once the toy with the highest pitch was identified, an additional toy was made by attaching two identical discs together to assess the impact of thickness on the sound. The new toy was labeled by adding "II" to its identifier (e.g., D1R5 II).
The same method was used to measure the sound, and the results were compared to identify the impact of thickness.
Designing a Portable Dryer
Based on the findings, a mini-sized product prototype was created to test the application of the button toy’s principles in designing a portable dryer.
Results
Characteristics Observed When the Button Toy Spins
The spinning process of the button toy can be divided into two stages: twisting and untwisting of the string.
Initially, the string is twisted by rotating the handles in the same direction. Once the string is fully twisted, pulling the handles tight causes the string to untwist, spinning the disc in one direction. As the string untwists and loosens, the disc continues to spin due to inertia, and the string begins to twist in the opposite direction. When the string is fully twisted in the opposite direction, the disc temporarily stops, and pulling the string tight again causes it to spin in the reverse direction.
As the disc spins, it emits a buzzing sound that starts low and becomes higher-pitched as the spinning speed increases. The highest-pitched sound occurs when the string is fully untwisted, and the disc is spinning at its maximum speed.
Sound Measurement Results
The results of the sound measurements for the four button toys are as follows:
- D1R5 produced the highest average sound at 107.0 dB.
- D2R5, D1R10, and D2R10 followed in descending order, with D2R10 producing the lowest sound at 52.3 dB.
It was observed that, when the disc size was the same, toys with shorter distances between the holes produced higher-pitched sounds. Similarly, when the hole distance was the same, smaller discs produced higher-pitched sounds.
When the thickness of the D1R5 toy was increased (D1R5 II), the average sound decreased to 92.3 dB, indicating that thinner discs produced higher-pitched sounds. A graph of the results of all five toys is presented for clarity.
Analysis of Why D1R5 Produced the Highest-Pitched Sound
Like a car engine, the higher the RPM, the higher the pitch of the sound produced by the button toy. To produce the highest-pitched sound, the disc must spin as fast as possible.
Several factors, such as the type of string or friction, could affect the force transferred to the disc. However, in this experiment, the string was standardized, so the focus was on the disc’s characteristics. A smaller, thinner disc and a shorter distance between the holes led to faster spinning and a higher-pitched sound due to reduced air resistance and friction. Additionally, although research suggests that a wider distance between the holes should increase RPM, this experiment showed that it was more difficult to spin toys with wider hole distances, potentially affecting the results.
Portable Dryer Applying the Principle of the Spinning Button Toy
As demonstrated in this experiment, the spinning button toy can rotate at incredibly high speeds. This high RPM generates a centrifugal force, which has been utilized in practical applications such as blood centrifuges. Watching the toy spin rapidly in one direction before reversing direction reminded me of how dogs shake their bodies to remove water after getting wet. By shaking their bodies side to side, the water on their fur is flung off due to the centrifugal force, helping them dry off. Similarly, in household washing machines, the drying cycle uses centrifugal force generated by the rapid rotation of the drum to remove water from clothes.
By applying the high RPM and resulting centrifugal force of the spinning button toy, we can create a portable dryer. This could be especially useful for family camping trips or after swimming at the beach in the summer, where a quick and effective method for drying clothes is needed.
The concept for the portable dryer is illustrated below. The device would consist of a cylindrical mesh container where wet clothes can be placed. In the center of the container would be a large disc, similar to a button, with strings running through it, resembling the spinning button toy. Two people could hold either end of the string to spin the dryer, or one end could be fixed to a pole while the other end is pulled to spin it, much like how the button toy is spun to create a drying effect.
