The purpose of this publication is to present a novel approach to the demonstration of the Dzhanibekov effect. The main idea of our version is to use a lightweight spinning top of a spherical external form but distinct principal moments of inertia floating in the upward flow of air. As a result, the Dzhanibekov effect can be easily demonstrated…

If a smooth ball is dropped vertically without spin on a smooth horizontal surface then one might expect the ball to bounce vertically without spin. If it does not then the centre of mass of the ball does not coincide with its geometric centre. An experiment is described where a billiard ball and a superball are deliberately biassed by adding a…

In order to describe the velocity of two bodies after they collide, Newton developed a phenomenological equation known as 'Newton's experimental law' (NEL). In this way, he was able to practically bypass the complication involving the details of the force that occurs during the collision of the two bodies. Today, we use NEL together with momentum…

If a ball rolls at constant speed on a horizontal surface about a horizontal axis then the angular velocity is easily measured. If the ball is projected with additional spin about the vertical axis, then the rotation axis is tilted and it is more difficult to measure the rotation speed. A few examples are presented to show how the separate topspin…

The tidal forces generated by a black hole can be so powerful that they cause unlimited stretching, known as spaghettification. A detailed analysis of this phenomenon requires the use of Einstein's theory of general relativity. The aim of this paper is to offer an up-to-date and accessible analysis of spaghettification, in which the complex…

In this paper we consider the well-known experiment with the 'heavy' newspaper that breaks a stick that it is laid on. Using several appropriate control experiments we show that the currently invoked explanation using atmospheric pressure cannot be correct. We perform a theoretical analysis and propose a new explanation based on the rotational…

We propose an experimental analogy to verify Kepler's second law using a spherical pendulum. We made a movie of a closed elliptical orbit of the pendulum and extracted the data position using the Tracker software. Analyzing the data, we measured the areas that the position vector sweeps showing the validity of Kepler's second law.

Newton's cradle is often discussed in science classrooms as a clear example of the laws of conservation of momentum and energy although it has been shown that this use is somewhat misleading. Approaches to understanding the behaviour of this apparatus are often over-simplified and deficient or over-complex and with little impact among teachers. In…

When a ball bounces obliquely on a horizontal surface, the bottom of the ball stretches horizontally and then vibrates backward. The resulting ball spin depends sensitively on the transverse vibration frequency. A simple model is presented to describe the effect, showing how the stored elastic energy can result in additional spin.

In the transition from classical to modern physics, the idea of taking some certain quantities as distinct or bounded values and keeping the rest continuous has proved useful in dealing with many problems. In this paper we assume an upper bound on the velocity of classical particles and indicate that applying this assumption to electromagnetism…

Students' understanding of forces in circular motion is often incomplete. The problems are not limited to confusions about centripetal acceleration and centrifugal forces. This paper considers possible effects of different interventions by a teacher who has discovered the many types of free-body diagrams drawn by students for circular motion in a…

Large drop towers let you experience a couple of seconds of nearly free fall before stopping gracefully in magnetic brakes or bouncing a number of times on compressed air, as in the Turbo Drop tower considered in this work, where many complementary representations are used. An accelerometer taken along on the ride captured the forces experienced…

Newton's cradle is a well-known physics toy that is commonly used by teachers to demonstrate conservation laws in mechanics. It can also be used to investigate the physics of colliding objects, by recording motion of the balls on video film. Various experiments are described using 3-ball and 5-ball cradles, showing how different types of collision…

The vertical bounce of a plastic egg was investigated by dropping the egg on a horizontal surface and filming the result with a video camera. If the egg is dropped on one end then it bounces just like a spherical ball. If the top end of the egg is pointing forwards or backwards when it lands on the surface, or if the egg is spinning when it lands,…

The conservation law of energy and momentum can be examined and demonstrated by a well-known collision experiment. In this experiment, several identical elastic balls are suspended from a horizontal frame. When the ball at one end is pulled aside and released, thus allowing it to swing like a pendulum, it hits the next ball. The outcome is…