The application of physico-chemical principles has been routinely used to explain various physiological concepts. The Nernst equation is one example of this, used to predict the potential difference created by the transmembrane ion gradient resulting from uneven ion distribution within cellular compartments and the interstitial space. This…

The stately fall of magnets through conducting pipes is a favorite classroom and laboratory activity used in teaching electromagnetic induction, Lenz's law, eddy currents, electromagnetic braking, and even Newton's third law. When a neodymium magnet is used, the terminal velocity is reached in just a few milliseconds as the induced eddy currents…

An experiment is described where a pendulum bob was allowed to roll back and forth across an inclined plane. The period of oscillation is larger than that for oscillation in a vertical plane, in part because the effective value of "g" is reduced on an inclined plane. The experiment highlights the differences between all three common…

The ability to understand the relationship between the reversal potential and the membrane potential is a fundamental skill that must be mastered by students studying membrane excitability. To clarify this relationship, we have reframed a classic experiment carried out by Hodgkin and Katz, where we compare graphically the membrane potential at…

It is well known that Newton's work on mechanics depended in a crucial way on the previous observations of Galileo. The key insight of Galileo was that one can analyze the motion of bodies using experiments and mathematical equations. One experimental observation that roughly emerges from this work in modern terms is that two objects of different…

The ideal gas law, "PV = nRT," is one of the simplest physical laws in nature that is introduced to students as early as in high school and first year in college. In this equation, "P" stands for pressure, "V" is the volume, "n" is the amount expressed in mole, "T" is the temperature in Kelvin…

We discuss the limits of the equation of the period of a simple pendulum, T[subscript s] = 2[pi][square root]l/g, frequently used in high-school and university classrooms to measure the acceleration of gravity. We evaluate the relative error in determining the acceleration of gravity with this simple equation instead of a more realistic one,…

A glass of water covered with a disk with a hole in it can be turned upside down without spilling the water in the glass, provided the hole is small enough and the disk is pressed against the rim of the glass. A quasistatic numerical simulation based on hydrostatic pressure and surface tension of water was used calculate the critical hole diameter…

The drag effect on a falling ball caused by air is a conventional subject in the most well-known textbooks of classical mechanics and fluid dynamics. Further, there are some papers that employ video analysis to track objects movements in the air making it possible to obtain position data as a function of time and its graphs. However, none of them…

In a paper (posthumously) co-authored by Isaac Newton himself, the primacy of geometric notions in pedagogical expositions of centripetal acceleration has been clearly asserted. In the present paper we demonstrate how this pedagogical prerogative can inform the design of an experiment involving an accelerometer-equipped smartphone rotating…

Simple experiments for which differential equations cannot be solved analytically can be addressed using an effective model that satisfactorily reproduces the experimental data. In this work, the 1D kinematics of a remote-control model (toy) car was studied experimentally and its dynamical equation modelled. In the experiment, maximum power was…

It is generally agreed that making real-world connections in mathematics teaching increases students' motivation and interest and contributes to meaningful and permanent learning. In this paper we propose a simple and fast activity to find a rectangular hyperbola in real life and we show how to operate the data to retrieve a straight line. Since…

This article describes an experiment that can be done in the classroom in a simple way, with the support of a "homemade" device or as a laboratory practice with the support of PASCO equipment. Through a theory-practice sequence, kinematic and dynamic equations were checked with qualitative and quantitative analysis, emphasizing the…

The Doppler effect has seen widespread use in the past hundred years. It is used for medical imaging, for measuring speed, temperature, direction, etc, and it makes the spatial relations of motion easy to map. The Doppler effect also allows GPS receivers to measure the speed of a vehicle significantly more accurately than dashboard speedometers.…

A physical experiment concerning the moment of inertia of a rigid disk is described. Basic physical quantities such as the moment of inertia and torque are very important in elementary physics courses. This experiment was designed to improve students' understanding of the relation between the rigid moment of inertia and torque. The moment of…