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Chapter 12.1. Temperature and Thermal Energy. What makes a hot body hot?. In the 18th century scientists came up with the caloric theory of heat In this theory an invisible substance called “caloric” created heat.
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Chapter 12.1 Temperature and Thermal Energy
In the 18th century scientists came up with the caloric theory of heat • In this theory an invisible substance called “caloric” created heat. • Only in the mid-nineteenth century did scientists develop the kinetic-molecular theory. • This stated that as the particles moved faster they created a greater kinetic energy and thus heat.
According to the kinetic-molecular theory hot bodies have a greater average thermal energy than a cold body. • Temperature is measured on a definite scale. • Thermal energy is proportional to the number of particles in the object, while temperature is not.
Temperature is measured using a process called conduction. • When your body and the thermometer are at the same temperature they are at thermal equilibrium. • Thermometers contain a liquid that will expand when heated and retract when cooled, thus the liquid rises and falls.
Each interval on the kelvin scale is called a kelvin. • A reading of 0oC is where water freezes. • However, a reading of 0K is absolute zero. • At absolute zero all molecules cease to move. • We have never been able to create conditions of absolute zero.
Heat is the energy that flows between two objects due to a temperature difference. • The transfer of energy through electro-magnetic waves is radiation. • The motion of fluid due to a temperature difference is called convection. • The specific heat of a material is the amount of energy needed to change its temperature
Specific Heat of Common Substances Material Specific heat Material Specific heat J/kg x K J/kg x K aluminum 903 lead 130 brass 376 methanol 2450 carbon 710 silver 235 copper 385 steam 2020 glass 664 water 4180 ice 2060 zinc 388 iron 450
Heat Transfer • Q=mCDT = mC(Tfinal – T initial) • T= temperature (K) • m= mass (Kg) • Q= heat gained or lost (J) • C=specific heat (J/Kg*K) heat transfer. Chart. Heart Transfer. N.p., n.d. Web. 11 Jan. 2011. <http://www.aos.wisc.edu/ ~aalopez/aos101/wk5.html>.
heat transfer. Chart. Heart Transfer. N.p., n.d. Web. 11 Jan. 2011. <http://www.aos.wisc.edu/ ~aalopez/aos101/wk5.html>.