How can a dead rattlesnake strike a reaching hand?
The answer is in this lesson.
Because of their highly poisonous venom, rattlesnakes pose a danger to humans. When the snakes are discovered in residential areas, they are usually killed. However, the death of a rattlesnake does not immediately decrease its danger. Indeed, numerous people have made the error of reaching for a dead snake to remove it. Although the snake may have been dead for as long as 30 minutes, it can still strike a person, burying its fangs into a reaching hand and delivering its venom.
What Is Physics?
One of the principal branches of physics and engineering is thermodynamics, which is the study and application of the thermal energy (often called the internal energy) of systems. One of the central concepts of thermodynamics is temperature, which we begin to explore in the next section. Since childhood, you have been developing a working knowledge of thermal energy and temperature. For example, you know to be cautious with hot foods and hot stoves and to store perishable foods in cool or cold compartments. You also know how to control the temperature inside home and car, and how to protect yourself from wind chill and sunburn.
Examples of how thermodynamics figures into everyday engineering and science are countless. Automobile engineers are concerned with the heating of a car engine, such as during a NASCAR race. Food engineers are concerned both with the proper heating of foods, such as pizzas being microwaved, and with the proper cooling of foods, such as TV dinners being quickly frozen at a processing plant. Geologists are concerned with the transfer of thermal energy in an El Nino event and in the gradual warming of ice expanses in the Arctic and Antarctic. Agricultural engineers are concerned with the weather conditions that determine whether the agriculture of a country thrives or vanishes. Medical engineers are concerned with how a patient’s temperature might distinguish between a benign viral infection and a cancerous growth.
The starting point in our discussion of thermodynamics is the concept of temperature and how it is measured.
Fig. 18-1 Some temperatures on the Kelvin scale. Temperature T = 0 corresponds to 10−∞ and can-not be plotted on this logarithmic scale.
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