Discusses the difficulties with the standard model for introduction of attractive forces into the van der Waals equation. Presents an analysis in terms of force and time delays and an alternative analysis for more advanced students in terms of energy. (JRH)

Discusses the microscopic interpretation of thermal conductivity of various forms of matter. Forms considered include gases, metals, and insulators. (JN)

Explores the theory behind the correlation between warm rain, rapid snowmelt, and the subsequent runoff using the concepts of enthalpy, thermal transfer, and energy transfer. Concludes that rapid runoff is not a consequence of rain per se but of the high humidities associated with the rain. (JRH)

Explains a change in sign convention for thermodynamic work. (CCM)

Reviews "Thermodynamics" (Cross Educational Software) and "Calorimetry and Thermodynamics" (Educational Materials and Equipment Company). The first package has seven programs (briefly described) while the second package contains virtually an identical subset of the Cross package. (JN)

Describes a paradox in the equation for thermal expansion. If the calculations for heating a rod and subsequently cooling a rod are determined, the new length of the cool rod is shorter than expected. (PR)

Describes a demonstration using a heated wire to illustrate the phase change from the body-centered cubic form of iron to the face-centered cubic form. (MLH)

Presents a method to measure the mass of a definite amount of a gas that occupies a known volume at a given pressure in order to determine experimentally the root mean square speed of molecules of a gas. (JRH)

Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…

Scientists often use the "slingshot effect" (also called the "gravity assist") of the gravitational field of a planet to increase or decrease the velocity of a spacecraft. Examples of this effect, puzzling aspects, a qualitative explanation, details of necessary calculations, a thermodynamic analogy, and other topics are discussed. (JN)

A thermodynamic analysis of the properties of otto/diesel engines during the time they operate with open chambers illustrates applicability of thermodynamics to real systems, demonstrates how delivered power is controlled, and explains the source of air pollution in terms of thermodynamic laws. (Author/JN)

Fire-fighting considerations teachers may want to raise with students in physics classes are discussed. Concepts involved in extinguishing fires and the operation of fire equipment are detailed. (CW)

Examines problems that occur with the vocabulary used in physics textbooks related to heat and energy. Discusses the concepts of thermal energy and temperature, conservation of energy laws, and the first law of thermodynamics. (MDH)

An exercise that gives students a chance to use the equations of state for both an ideal gas and for an adiabatic process in determining the points at which heat flow reverses direction and at which the working substance reaches its maximum temperature is demonstrated. (KR)

Describes some scientific concepts illustrated by and sources of Sterling engines. Includes an elementary version of their theory. (JN)