The determination of the speed of sound in air is a classical experiment, usually performed with a resonance tube apparatus. The measured value can be checked against Eq. (1), which describes the temperature dependence of the speed of sound in dry air. A modern implementation of this speed of sound investigation uses an Arduino Uno microcontroller…

Video analysis helps students to connect physical, mathematical, and graphical models with the phenomena that the models represent and improves student kinematic graph interpretation skills. The wide-spread availability of easy to use software packages like Logger Pro (Vernier), Capstone (PASCO), and Tracker have led to many introductory physics…

The use of video analysis for the study of motion and forces is well established in the worlds of physics and biomechanics. The issue of parallax error, sometimes referred to as perspective error or scaling error, when videotaping a moving object is known, and the experimenter is often counseled to be "far away." However, "far…

In an article in this journal, it was shown that air resistance could never be a significant source of error in typical free-fall experiments in introductory physics laboratories. Since projectile motion is the two-dimensional version of the free-fall experiment and usually follows the former experiment in such laboratories, it seemed natural to…

When grading students' quizzes and exams, I find that students are seemingly always changing their answers from the right answer to the wrong answer. In fact, I have cautioned students against changing their answer. Colleagues have made similar observations and some books on test-taking strategies advise against answer-changing. In an effort to…

Systematic errors can cause measurements to deviate from the actual value of the quantity being measured. Faulty equipment (such as a meterstick that is not marked correctly), inaccurate calibration of measuring devices (such as a scale to measure mass that has not been properly zeroed), and improper use of equipment by the experimenter (such as…

At our university, students in introductory physics classes perform a laboratory exercise to measure the range of a projectile fired at an assigned angle. A set of photogates is used to determine the initial velocity of the projectile (the launch velocity). We noticed a systematic deviation between the experimentally measured range and the range…

Early in their study of one-dimensional kinematics, my students build an algebraic model that describes the effects of a rolling ball's (perpendicular) collision with a wall. The goal is for the model to predict the ball's velocity when it returns to a fixed point approximately 50-100 cm from the wall as a function of its velocity as it passes…

We learn best by example--this adage is probably as old as teaching itself. In my own classroom, I have found that very often the students learn best from the "negative" examples. Perhaps, this shouldn't come as a surprise at all. After all, we don't react strongly to the norm--but an obvious deviation from the norm may attract our attention and…

Discusses student errors occurring on the New York Regents Examinations given over the last ten years. (SL)