A rocket must carry the fuel it expels in order to accelerate its structure and payload. The rocket equation relates the change in speed to the fuel mass expelled. To launch a spacecraft into Earth orbit requires a multi-stage rocket, since otherwise the mass of fuel required would be prohibitive. While the details vary among historical and…

The distinction between pressure in a liquid and in a gas is often treated in a cursory way, or not treated at all, even in university level textbooks. Most texts fail to point out the relation between pressure and density in a gas as compared to pressure in a--virtually incompressible--liquid. In many instances this also results in a dismissive…

Archimedes' principle is one of the foundation subjects in physics. Normally the principle is exemplified by reference to floating boats. However, Archimedes' principle also applies to objects embedded in waterlogged ground, which can lead to the surprising result of an object weighing several tons being lifted. A practical example is presented of…

In this article we consider a well-known simple, very accessible demonstration of surface tension with a small boat propelled by substances that change the surface tension of water. A simple quantitative evaluation is provided that matches well with experimental data. A modification to the experiment is proposed allowing it to continue for a long…

This work presents a sequence to introduce resistive gas sensors in the classroom. It explains the physical principle of the metal oxide semiconductor sensors and exemplifies its real interfacing through the sensor model MQ-2. Besides, it also presents the design of two electronic systems to indicate the level of alcohol concentration in the air,…

Fusion energy research is 'mission oriented' big-science. It has both rapid progress and a reputation for being forever distant that excites many with a curiosity for science. However, it is difficult to give time to in lesson plans given both its lack of associated learning objectives and complexity. Outreach at the Fusion Centre for Doctoral…

The "safety lamp" invented by Humphrey Davy in 1815 utilised the cooling effect of metal gauze to prevent the flame of a candle or oil lamp (essential for illumination in mines) from passing through such a screen. It is therefore rendered unable to ignite any potentially explosive mixture of air and methane in the atmosphere surrounding…

A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

This paper presents a comparative study of the thermal efficiencies of mechanical heat engines by using a graphical approach based on the pressure-volume ("P-V") diagram. Three types of idealized thermodynamic cycles--the Otto, the Diesel and the Brayton--are compared in pairs. Given the same temperature range within which the engines…

The recent introduction of inexpensive high-speed cameras offers a new experimental approach to many simple but fast-occurring events in physics. In this paper, the authors present two simple demonstration experiments recorded with high-speed cameras in the fields of gas dynamics and thermal physics. The experiments feature vapour pressure effects…

Millikan's oil-drop experiment is one of the classic experiments from the history of physics. Due to its content (the determination of the elementary charge) it is also among those experiments that are frequently used and discussed in teaching situations. Disappointingly, a review of the educational literature on this experiment reveals that its…

Discusses statistics concerning world energy requirements and supplies of different types of fuels. Also discusses the storage and transmission of energy and pollution problems related to energy utilization. (MLH)

Explores the possibility of installing offshore windmills to provide electricity and to save fuel for the United Kingdom. Favors their deployment in clusters to facilitate supervision and minimize cost. Discusses the power output and the cost involved and urges their quick development. (GA)

Explains the function of a central heating system and calculates the total heat energy required to heat a house. Estimates annual heat requirement and amount of fuel needed. Gives detailed calculation of heat required for a particular house as an example. (G A)

Looks at the process of photosynthesis in a new light, to show that distinct possibilities exist for using photosynthesis to harvest fuel, food, fibre, and chemicals. (GA)