A loop-the-loop experiment usually involves a ball rolling around a vertical loop. A different version of the experiment is described where a nut was allowed to slide around a vertical loop. In both experiments there is a large decrease in kinetic energy when the ball or the nut first enters the loop.

A collision of one object with two or more objects is relatively complicated in general, but a simple example is provided by Newton's cradle since all the objects are identical and in line. In the present paper, an experiment is described where a heavy mallet collides head-on with two billiard balls. The two conservation equations indicate that…

Races between moving objects are an engaging way to teach dynamics to introductory physics students. One standard example consists in racing hollow and solid cylinders as they roll down an inclined plane. Another striking demonstration is a race between two marbles on side-by-side tracks that start and end together, but with one track taking 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…

The problem of a disc or cylinder initially rolling with slipping on a surface and subsequently transitioning to rolling without slipping is often cited in textbooks. Students struggle to qualitatively understand the difference between kinetic and static frictional forces--i.e., whereas the magnitude of the former is known, that of the latter can…

In this work, a simple rocking pendulum, in a circular arc shape, is presented. The idea is to put a rigid arc on a clean flat surface of glass and leave it to oscillate under the effect of a little impulse. Then, the periodic time of this arc pendulum's motion is experimentally determined. The mathematical analysis of the arc's motion is derived…

The law of conservation of momentum is a fundamental law of nature. It states that the momentum of an isolated system is conserved. In high school or introductory-level physics courses, for simplicity, teachers and textbooks always use collisions in one dimension as the examples to introduce the concept of conservation of momentum. To solve simple…

A rocket in free space accelerates from rest by continuously expelling fuel; as its speed increases, its mass decreases. At what speed (and remaining mass) does the rocket carry maximum momentum? Maximum kinetic energy? The answers provide insights into the dynamics of variable-mass systems, and have applications to planetary defense that are…

Owing to the presence of the Coriolis effect, the rotation of Earth has a multitude of surprising consequences that make the mechanics of the atmosphere or the oceans different from that of a fluid in a container. Since the Coriolis effect also captures the imagination of screenwriters, contributing to the continual exposure of students to bogus…

The Gaussian gun is an arrangement of magnets and ball bearings (pictured in Fig. 1) such that--when the leftmost ball is released--the rightmost ball is ejected at high speeds. The device has been described in several articles on energy education. The sudden appearance of kinetic energy offers a productive context for considering a range of…

We report on an investigation of student thinking about steady-state pipe flow of an incompressible fluid. About 250 undergraduate engineering students were given a test consisting of two hydrodynamics questions, combining multiple-choice format with subsequent open-ended explanations. There is substantial evidence that students have difficulty…

A spreadsheet plotting assignment of real-life data from a racecar is employed to help students master the relationships among speed, acceleration, and distance. The racecar application will capture the imagination and interest of the student. The data is obtained by reading speedometer values from a YouTube video for 40 s as a racecar accelerates…

We investigate the motion of fidget spinners of different configurations with the help of simple devices. Physical quantities associated with the fidget spinner motion like angular speed, moment of inertia and kinetic energy are determined and compared in different configurations. A configurable modification of the fidget spinners is done to…

A simple experiment for students is to measure the coefficient of restitution (COR) for a vertical bounce on a horizontal surface. In this paper, measurements are presented of the COR for a tennis ball bouncing at an oblique angle on a horizontal surface. Changes in the horizontal and rotation speeds were also measured, by filming the bounce with…

Kinematic models are often very useful. The back and forth throw of a ball between two ice skaters may help us appreciate the meson exchange theory of Yukawa. If the skaters throw the balls at each other, they move backward, which is equivalent to a repulsive force between them. On the other hand, if they snatch the ball from each other, the…