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…

Many introductory physics courses begin with the teaching of motion and kinematics. This naturally leads to the use of constant acceleration equations to solve various problems involving common motions (free fall being a notable example). Students can sometimes get the impression that these equations are the only thing they need to remember in…

The aim of this paper is to propose a method for solving head-on elastic collisions, without algebraic complications, to emphasize the use of the fundamental conservations laws. Head-on elastic collisions are treated in many physics textbooks as examples of conservation of momentum and kinetic energy.

To familiarize first-year students with the important ingredients of a physics experiment, we offer them a project close to their daily life: measuring the effect of air resistance on a bicycle. Experiments are done with a bicycle freewheeling on a downhill slope. The data are compared with equations of motions corresponding to different models…

As we typically teach in an introductory mechanics course, choosing a "good" coordinate frame with convenient axes may present a major simplification to a problem. Additionally, knowing some conserved quantities provides an extremely powerful problem-solving tool. While the former idea is typically discussed in the context of…

Newton's second law is one of the cornerstones of the introductory physics curriculum, but it can still trouble a large number of students well after its introduction, hobbling their ability to apply the concept to problem solving and to related concepts, such as momentum, circular motion, and orbits. While there are several possibilities for…

Halfway through the 2015 AFC Championship game between the New England Patriots and Indianapolis Colts, game officials discovered that the Patriots were using underinflated footballs on their offensive snaps. A controversy ensued because the Patriots had actually supplied these balls to the game's referee just hours before kickoff. Athletes and…

Energy is a critical concept in physics problem-solving, but is often a major source of confusion for students if the presentation is not carefully crafted by the instructor or the textbook. A common approach to problems involving deformable or rotating systems that has been discussed in the literature is to employ the work-kinetic energy theorem…

As the topic of relativity is developed in a first-year physics class, there seems to be a tendency to move as quickly as possible to the fascinating ideas set forth in Einstein's special theory of relativity. In this paper we linger a little with the Galilean side of relativity and discuss an intriguing problem and its solution to illustrate a…

Presents exercises that analyze the additive property of energy. Concludes that if a body has more than one component of energy depending on the same physical quantity, the body's total energy will be the algebraic sum of the components if a linear relationship exists between the energy components and that physical quantity. (JRH)

Describes the graphing calculator as a new graphical approach to standard physics problems. Presents a collision problem to illustrate its use. (JRH)

Solutions to quadratic equations found in solving physics problems sometimes make no sense. Investigates problems in which solutions, such as negative numbers, have significant physical meaning in the problem. Problems are chosen from the topics of kinematics, conservation of mechanical energy, inelastic and elastic collisions, electrostatics, and…

Uses the problem of determining when a car and truck traveling at the same speed will collide after the truck has applied its brakes to illustrate the need to consider boundary conditions when solving problems in elementary mechanics. (MDH)