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Engineering: The challenge of temperature
Engineering is about extending the horizons of society by solving technical problems,...
Engineering is about extending the horizons of society by solving technical problems, ranging from the meeting of basic human needs for food and shelter to the generation of wealth by trade. This unit looks at the impact of changes in temperature on a variety of objects and looks at the problem of boiling water.
After studying this unit you should be able to:
- relate the temperature of a solid to the mean kinetic energy of its atoms;
- use models for thermally induced effects that involve linear, exponential and step changes;
- use exponentials, logarithms and graphical methods to interpret data from a thermally activated process in terms of Arrhenius's law;
- identify the changes of phase taking place in a variety of critical phenomena;
- provide examples of gradual, accelerating and sudden changes in the properties of materials that accompany changes in temperature;
- develop and extend performance specifications for devices that respond to changes in temperature.
- Current section: Introduction
- Learning outcomes
- 1 Temperature – problem or solution?
- 2 Getting into hot water
- 3 Gradual temperature effects
- 4 Accelerating temperature effects
- 4.1 Characteristics of processes activated by thermal energy
- 4.2 Energy distribution
- 4.3 Thermally activated processes
- 4.4 Summary of Section 4
- 5 Sudden temperature effects
- 6 The water boiler again
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Engineering: The challenge of temperature
In this unit we examine one factor that very often seems to be found skulking around close to problems and solutions: temperature.
Almost whatever we do, wherever we are, temperature changes. Stay in the same spot and you'll find daytime and night-time temperatures can be markedly different. You may even find significant changes in temperature during the day. When moving you can encounter more rapid variations. For example, an aircraft might leave a tropical runway where the air temperature is thirty degrees Celsius and climb within minutes to a height where the outside temperature is minus fifty degrees.
It turns out that almost all the properties of a material change with temperature. So, anything you make will to some extent be sensitive to temperature. That sensitivity needs to be known about. ‘What if the temperature changes?’ is an excellent prompt for engineers.
There are advantages and disadvantages to thermal sensitivity and some of these are explored in her. On the one hand, we can do amazing things with thermal energy, such as moving matter around within a solid without risking melting or changing the basic shape of a component. On the other hand, it can be a real nuisance. It can make magnetic disks ‘forget’. It can leave materials ‘sapped’ of their strength. Just a few degrees of temperature change can make some things unrecognisably different. Temperature really does present a universal challenge that must be faced – ignore it at your peril.
This unit is an adapted extract from the Open University course
Copyright & revisions
Originally published: Friday, 22nd July 2011
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