The Double Asteroid Redirection Test (DART) is a National Aeronautics and Space Administration--European Space Agency collaborative mission to test the feasibility of defending Earth from a catastrophic asteroid impact by using a spacecraft to deflect the asteroid away from the planet. Launched on Nov. 23, 2021, the DART spacecraft will intercept…

Ampère's law is presented in introductory physics as a relation between the line integral of the magnetic field around a closed loop and the net current crossing any open surface spanning that loop. By allowing the surface to pass between the plates of a charging parallel-plate capacitor, Maxwell realized that this law is incomplete and introduced…

In one of the Faraday's experiments an electric current is induced in a conducting loop when a magnet in front of it moves towards or away from the loop. While the direction of circulation of the electric current in the loop has only two options, it depends on three experimental conditions that generate eight cases. Even though the Faraday law or…

Archimedes' principle has been and still is a complicated concept to understand by introductory students, especially as typically stated in physics textbooks. Take for example its statement by Bierman: "When a body is fully or partially submerged in a fluid, a buoyant force from the surrounding fluid acts on the body. The force is directed…

Exciting examples of physics principles illuminate the power and scope of our discipline. In this paper, we discuss a conservation of energy example for an introductory course. Energy conservation is applied to bird and dinosaur eggs to derive a method to predict the incubation period and the embryonic metabolism solely from the egg geometry. The…

The calculation of the magnetic field produced by a loop current using the Biot-Savart law is a very typical exercise in introductory university physics. However, the cases studied are limited, in most textbooks, only the circular arrangement is treated. In this article, we calculate the magnetic field of an elliptical loop current along an axis…

In many introductory physics classes, diffraction of light is introduced first, then more advanced diffraction topics such as x-ray diffraction, Bragg's law, and crystallography are covered. Since using x-rays raises safety concerns and atomic spacing in a crystal is not easy to change, microwaves with macroscopic crystals have been used to study…

The classic brachistrochrone problem is standard material in intermediate mechanics. Many variations exist including some accessible to introductory students. While a quantitative solution isn't feasible in introductory classes, qualitative discussions can be very beneficial since kinematics, Newton's laws, energy conservation, and motion along…

While the three laws of conservation of energy, momentum, and angular momentum are all mentioned in introductory textbooks, there are few experiments through which students can investigate the conservation of angular momentum. Most experiments consist of collisions between rotating disks, in which one disk is dropped on another, or in which the…

Popular accounts of exciting discoveries often draw students to physics and astronomy, but at the introductory level it is challenging to connect with these in a meaningful way. The use of real astronomical data in the classroom can help bridge this gap and build valuable quantitative and scientific reasoning skills. This paper presents a strategy…

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…

Many of the old demonstrations in electricity and magnetism can be performed more effectively and with greater visual appeal by using newly available neodymium magnets and color LEDs. For this reason several demonstrations, commonly used for teaching electromagnetic induction and Lenz's law, have received renewed attention in recent years. In…

Most springs do not simply obey Hooke's law because they are constructed to have an initial tension, which must be overcome before normal elongation occurs. This property, well known to engineers, is universally neglected in elementary physics courses. In particular, the standard simple harmonic motion experiment omits any discussion of this…

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…

The change in enthalpy of a chemical reaction conducted at constant pressure is equal to the heat of the reaction plus the nonexpansion work of the reaction, ?H = qP + w[subscript additional]. After deriving that relationship, most general and physical chemistry textbooks set w[subscript additional] = 0 to arrive at the claim that ?H = qP, and…