When parents and children play on slides together, they often find that adults slide faster than children.Similarly, with skis and bicycles, it is recalled that ``the heavier the bike, the faster it moves''.
However, as we learned in high school physics, the magnitude of inertia and gravity are proportional to the mass of both heavy and light objects, so the fall acceleration is constant in a uniform gravitational field (uniform free fall). sex).Even on a slope with friction instead of free fall, the frictional force is proportional to the mass, so it is thought that all slides will slide at the same acceleration regardless of the mass.
Masaki Shiota, then a fourth-year student at Rikkyo University's Faculty of Science, took up the contradiction between the laws of physics learned in this textbook and life experiences as the theme of his graduation research, along with Professor Jiro Murata, who was in charge of his guidance. In response to the question, "Why does a heavier person slide faster on a slide?" We investigated the change in acceleration by actually sliding on a slide in the park.
As a result, it was found that the object reached a certain terminal velocity and slid on the slide instead of accelerating steadily.We also found that the terminal velocity increases as the weight of the object increases.In other words, it was clearly confirmed that the heavier the person, the faster they slid down the slide, not just because of imagination, but that the greater the mass, the greater the terminal velocity.
This is a new finding that it can be interpreted that the dynamic friction coefficient, which is usually learned to take a constant value, actually has velocity dependence and mass dependence.However, this property has only been confirmed for roller-type slides, and similar observations were made for traditional metal plate-type slides assumed in textbooks. andLong-distance sheet metal slides, pipe slides, stone slides, and other types of slides may yield different results.
The results of this research are said to have generated an unusual response as an academic paper, and are introduced as a good example of inquiry-based learning that resonates with curiosity and is approachable.
Paper information:[Physics education] Actual measurement study of the dynamic friction coefficient of slides
