Lecture 17.pdf - Heat and Internal Energy Heat is energy...

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- Prem Basnet Heat and Internal Energy Heat is energy that flows from a higher-temperature object to a lower-temperature object because of the difference in temperatures. Unit: Joule (J) “Heat is energy in transit from hot to cold.” 7/25/2018 PHYS 1020 1
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- Prem Basnet What is the source of heat? The internal energy of the hot object. internal energy = sum of molecular kinetic energy, molecular potential energy, etc. Increase in T increase molecular kinetic energy. 7/25/2018 PHYS 1020 2 Heat and Internal Energy
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- Prem Basnet Objects contain internal energy, they do not contain heat. Old (<1800) theory of heat heat is a fluid (the caloric) that flows from the hot object to the cold object. Disproved by Count Rumford, who showed that the frictional force doing work on a cannon increased the temperature of the cannon. 7/25/2018 PHYS 1020 3 Heat and Internal Energy
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- Prem Basnet Specific Heat Capacity The heat that must be supplied or removed to change the temperature of a substance is: Unit: J/(kg.K) 7/25/2018 PHYS 1020 4 Heat and Temperature Change: Specific Heat
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- Prem Basnet Some specific heat capacities: Substance c (J/kg.K) Aluminum 9.00 10 2 Copper 387 Glass 840 Ice (-15 ° C) 2.00 10 3 Iron or steel 452 Lead 128 Silver 235 Benzene 1740 Ethyl alcohol 2450 Glycerin 2410 Mercury 139 Water (15 ° C) 4186 7/25/2018 PHYS 1020 5 Heat and Temperature Change: Specific Heat
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