A classical mechanical structure with an internal degree of freedom is shown to reflect off a potential well. Such behavior is impossible for point-like or rigid classical particles. This numerical study provides insight for students studying internal energy and degrees of freedom.

A key concept in current fluid dynamics and its applications to biology and technology is a phenomenon known as wetting. Wetting is familiar from everyday life and is simply the ability of a liquid to stay in contact with a solid surface. The wettability depends on the properties of the liquid and the solid and can be characterized by the static…

Although the old problem of rotating liquid is described and solved in many textbooks and articles, the story still remains interesting. Intuitive understanding of the equipotential spatial surfaces is very difficult. This article is an attempt to present Newton's rotating tank in the light of the law of conservation of energy.

A good paradox has the viewer confused, but the best paradoxes lead the viewer to try to understand what is happening. One of the author's favorites is the hydrostatic paradox, in which a short and slender column of water supports a relatively enormous weight. He describes the paradox using an illustration of a student who weighs 60 points stands…

The laser pointer has been widely used to demonstrate some simple optics phenomena, like reflection, refraction, total reflection, and diffraction. However, the rays of laser light cannot be seen in the air because the scattered light is too weak. Many physics teachers use milk or smoke to visualize rays of laser light in physics labs, but it is…

Water rockets can be used in a variety of ways, from schools to planetariums, with very young kids or adults. We propose here simple forms to work with water rockets, going one step further than a simple launch. A smartphone can be used to film the launch and analyze its motion with video analysis or it can even be attached to the rocket, using…

A standard physics experiment for students is to measure the terminal velocity of an object in air or in glycerine. A more difficult challenge is to measure the terminal velocity in water since the depth of the water needs to be large or the object needs to be dropped in the water at a speed close to its terminal velocity. Results obtained by…

Apparatus catalogues of the first half of the 20th century contain a number of clever and simple devices for measuring the index of refraction of a liquid. In some cases students can put together one of these pieces of apparatus and then make their own measurements. The Gilley board was one of the devices that caught my eye, and I would like to…

The formation of waves as used for surfing close to the shore is described and explained, and linked to other wave topics that are covered in school science. Of course, there are differences because the wave activity is influenced by many factors, such as the weather and the shape of the shoreline, which make the wave patterns much more…

The physical problem of a body of water in a tank that drains through a hole in the base is a classical problem that has been studied since at least the time of Torricelli. To fixate this in a student's mind, one could ask them to visualize a bathtub that is being drained through the plughole or a bottle being drained through a tap. This problem…

Sound is an interesting topic for physics lessons at all ages. However, it is difficult to illustrate this ubiquitous phenomenon and many models do not adequately represent the properties of sound and thus promote unwanted conceptions. The experiment presented here avoids this by visualising sound itself with the help of the schlieren technique.…

In early January 2018, after days of subfreezing temperatures, a 20 m waterfall became mostly frozen with supercooled water pouring over the top of the frozen parts of the fall. A video was taken of the waterfalls and supercooled turbulent water flowing on the frozen surface as it turned into frazil ice right before our eyes. Frazil ice consists…

We propose a semiquantitative experiment that associates video-analysis and ordinary procedures of experimental physics whose objective is to investigate the dual character of Oobleck, a mixture of cornstarch in water, which appears thicker or thinner depending on how it is physically manipulated. The results are presented and interpreted taking…

Students may have some confusion understanding certain physical concepts and principles because of their abstract nature. Using analogies is one of the useful methods to help them more easily grasp abstract concepts to promote conceptual understanding. Bilaloglu classified analogies in four groups: (a) simple analogies, (b) storified analogies,…

In this article we consider a well-known simple, very accessible demonstration of surface tension with a small boat propelled by substances that change the surface tension of water. A simple quantitative evaluation is provided that matches well with experimental data. A modification to the experiment is proposed allowing it to continue for a long…