In the last 30 days

• Open/close How do wings work?

  Holger Babinsky 2003 Phys. Educ. 38 497 Tag this article

  Article References Full text PDF (364 KB)

  The popular explanation of lift is common, quick, sounds logical and gives the correct answer, yet also introduces misconceptions, uses a nonsensical physical argument and misleadingly invokes Bernoulli's equation. A simple analysis of pressure gradients and the curvature of streamlines is presented here to give a more correct explanation of lift.

• Open/close An analysis of the changes in ability and knowledge of students taking A-level physics and mathematics over a 35 year period

  Peter J Barham 2012 Phys. Educ. 47 162 Tag this article

  Article References Full text PDF (260 KB) Enhanced article HTML

  New undergraduate students arriving to study physics at the University of Bristol from 1975 onwards have all taken the same test of their knowledge and understanding of physics and mathematics. Many of the questions test knowledge of material that has been in the A-level syllabus for maths or physics throughout this period. The ability of incoming students to answer these questions declined significantly in the 1990s with average scores falling from around 75% up to 1990 to below 50% after 2000 against a background of increasing A-level grades of the entrants to the programme. It is suggested that changes in teaching and examination methods have caused students to be less able to carry out multi-stage calculations and that the introduction of modular examinations may have encouraged a culture where students tend to forget material learnt in previous modules.

• Open/close Narrow-band model

  J W Warren and B K Tanner 1977 Phys. Educ. 12 211 Tag this article

  Article References Full text PDF (201 KB)

• Open/close High accuracy optical inverse square law experiment using inexpensive light to frequency converters

  Keith H Wanser et al 2012 Phys. Educ. 47 174 Tag this article

  Article References Full text PDF (887 KB) Enhanced article HTML

  In this paper we report on the use of two different light to frequency converters, four different light sources, three of which are novel and inexpensive, and a hand held digital multimeter with a frequency counter, suitable for making accurate and rapid determination of the optical inverse square law exponent of − 2 to better than ± 0.005 over more than a factor of 100 in distance and a factor of 5 × 10 ⁵ variation of light intensity. Accurate data sets can be taken in 20–40 min, typically one minute per data point or less. The wide range of intensities measured makes a convincing demonstration of the optical inverse square law, and forms the basis for students learning how to plot log–log graphs over multiple orders of magnitude, extract power law exponents and learn about coefficients of determination. The extremely low cost of this high accuracy experiment and the ease of its implementation are appropriate for even the most modest budgets and least equipped high school physics laboratories.

• Open/close The 'radioactive dice' experiment: why is the 'half-life' slightly wrong?

  Arthur Murray and Ian Hart 2012 Phys. Educ. 47 197 Tag this article

  Article References Full text PDF (174 KB) Enhanced article HTML

  The 'radioactive dice' experiment is a commonly used classroom analogue to model the decay of radioactive nuclei. However, the value of the half-life obtained from this experiment differs significantly from that calculated for real nuclei decaying exponentially with the same decay constant. This article attempts to explain the discrepancy and suggests modifications to the experiment to minimize this effect.

• Open/close A simple demonstration of terminal velocity: an experimental approach based on Lenz's law

  Yajun Wei 2012 Phys. Educ. 47 265 Tag this article

  Article References Full text PDF (642 KB)

  No abstract
• Open/close Cosmic ray detection made easy

  Luis Peralta and Florbela Rego 2012 Phys. Educ. 47 143 Tag this article

  Article References Full text PDF (797 KB)

  No abstract
• Open/close Conceptual and laboratory exercise to apply Newton's second law to a system of many forces

  Carl E Mungan 2012 Phys. Educ. 47 274 Tag this article

  Article References Full text PDF (614 KB) Enhanced article HTML

  A pair of objects on an inclined plane are connected together by a string. The upper object is then connected to a fixed post via a spring. The situation is first analysed as a classroom exercise in using free-body diagrams to solve Newton's second law for a system of objects upon which many different kinds of force are acting (string tension, spring force, gravity, normal force, and friction). Next, the setup is replicated in the laboratory using rolling carts with attached force sensors (to measure the string and spring forces) and a motion detector (to measure the position, velocity and acceleration of the objects). After characterizing the rolling friction, cart masses, incline angle and spring constant, the kinematics and dynamics of the system can be accurately modelled with no free parameters. Representing the data in different ways, notably plotting quantities as a function of the displacement of the carts instead of elapsed time, greatly assists in their interpretation. For example, the acceleration of the carts lies along two straight lines when plotted in that way, the mechanical energy has a zigzag shape and the velocity of the carts traces out a set of joining half-ellipses in phase space.

• Open/close Making a fish tank cloud chamber

  Frances Green 2012 Phys. Educ. 47 338 Tag this article

  Article References Full text PDF (813 KB) Enhanced article HTML

  The cloud chambers described here are large, made from readily available parts, simple to set up and always work. With no source in the chamber, background radiation can be observed. A large chamber means that a long rod containing a weakly radioactive material can be introduced, increasing the chance of seeing decays. Details of equipment and construction are given.

• Open/close Rolling friction on a wheeled laboratory cart

  Carl E Mungan 2012 Phys. Educ. 47 288 Tag this article

  Article References Full text PDF (247 KB) Enhanced article HTML

  A simple model is developed that predicts the coefficient of rolling friction for an undriven laboratory cart on a track that is approximately independent of the mass loaded onto the cart and of the angle of inclination of the track. The model includes both deformation of the wheels/track and frictional torque at the axles/bearings. The concept of rolling friction is contrasted with the static or kinetic friction that in general is also present, such as for a cylinder or ball rolling along a horizontal or inclined surface.